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  • Polymer and Materials Science  (10,782)
  • Analytical Chemistry and Spectroscopy  (2,128)
  • 42.75
  • 2015-2019  (42)
  • 1970-1974  (12,910)
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  • 1
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.115
    Publication Date: 2018-12-13
    Description: Oligochaete wormen komen vooral in zoet water voor. Maar in brak water en zelfs in de volle zee komen enkele soorten voor. Bij onderzoek naar marien benthos werden deze dieren traditioneel niet tot op soort gedetermineerd, omdat ze klein en lastig te determineren zijn. Ze zijn echter niet veel lastiger dan de nauw verwante Polychaeta, die ook hele kleine vertegenwoordigers kennen. In dit artikel wordt een overzicht gegeven van de 32 soorten die nu uit het zoute water in ons land bekend zijn, waarvan er hier zes als nieuw voor de Nederlandse fauna gepresenteerd worden. De vondst van Heterodrilus subtilis in de Noordzee is zeer bijzonder, omdat deze soort verder alleen bekend is van het typemateriaal, dat ongeveer honderd jaar geleden in de Golf van Napels werd verzameld.
    Keywords: Oligochaeta ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 2
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.87
    Publication Date: 2018-12-13
    Description: Het laatste overzicht van de wantsen van de Nederlandse waddeneilanden dateert van 2012. Een opsomming wordt gegeven van 43 nieuwe eilandrecords, waaronder vijf soorten die voor het eerst op de waddeneilanden zijn waargenomen. In totaal zijn er nu 380 soorten wantsen van de Nederlandse waddeneilanden bekend.
    Keywords: Heteroptera ; Nederland ; Waddeneilanden ; verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 3
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.57
    Publication Date: 2018-12-13
    Description: Een overzicht wordt gegeven van waarnemingen van 33 soorten nieuwe of anderszins interessante soorten wantsen. Psallus aethiops (Miridae), Empicoris rubromaculatus (Reduviidae), Arocatus melanocephalus, Lygaeus simulans, Eremocoris fenestratus (Lygaeidae) en Nezara viridula (Pentatomidae) zijn nieuw voor de Nederlandse lijst, die daarmee nu 640 soorten telt. Naast nieuwe waarnemingen van zeldzame soorten wordt de recente uitbreiding van Cymatia rogenhoferi (Corixidae), Cardiastethus fasciiventris (Anthocoridae), Arocatus longiceps en Rhyparochromus vulgaris (Lygaeidae), Leptoglossus occidentalis (Coreidae), en Peribalus strictus en Rhaphigaster nebulosa (Pentatomidae) in kaart gebracht.
    Keywords: Heteroptera ; Nederland ; verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 4
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.101
    Publication Date: 2018-12-13
    Description: In Nederland komen tien soorten ruighaarkevers (genera Dryops en Pomatinus) voor. Ze leven langs oevers van stilstaande en stromende wateren. Het was een verrassing toen in 2014 een vrouwtje van de zeer zeldzame Dryops striatellus gevonden werd bij Bakkeveen (provincie Friesland). De soort was sinds 1960 niet meer in Nederland gevonden. In 2016 werd D. striatellus op een tweede locatie nabij Bakkeveen gevonden. In dit artikel geven wij informatie over de soort en presenteren bijzonderheden over de Friese populatie en haar habitat.
    Keywords: Coleoptera ; Dryopidae ; Dryops striatellus ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 5
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.11
    Publication Date: 2018-12-13
    Description: Op 14 oktober 2015 werd een halmvlieg met fraaie zwarte vlekken op de vleugels gefotografeerd in Hoogerheide (Noord-Brabant). Na vergelijking van foto’s werd geconcludeerd dat het moest gaan om Gampsocera numerata, welke determinatie later werd bevestigd. Reeds in 2009 bleek in België een mannetje van de soort gefotografeerd te zijn in een tuin in Evere. Ook in 2010 en 2015 is de soort in België gevonden. Dit zijn de eerste meldingen van G. numerata voor Nederland en België.
    Keywords: Diptera ; Chloropidae ; Gampsocera numerata ; Nederland ; België ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 6
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.49
    Publication Date: 2018-12-13
    Description: Recently two exotic tubeworms new to the fauna of the Netherlands have been recorded in inshore waters in the delta area: Desdemona ornata and Pseudopolydora paucibranchiata. Within the Polychaeta these worms belong to the group of the Sedentaria. These construct a tube, in which the body of the worm is hidden. The head and feeding appendages protrude from the opening. Most probably these tubes are a major factor in the transport of these animals around the world, as they provide excellent shelters when they are attached to the hull of a ship or commercially traded shellfish.
    Keywords: Polychaeta ; Pseudopolydora paucibranchiata ; Desdemona ornata ; Nederland ; verspreiding ; exoot ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 7
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.31
    Publication Date: 2018-12-13
    Description: De boszandbij Andrena coitana leek verdwenen uit Nederland. Veertig jaar na de laatste waarneming in 1975 is weer een populatie van deze soort gevonden, bij Epe in Gelderland. De boszandbij is een kleine soort, die mogelijk nog op sommige plaatsen over het hoofd gezien is. In dit artikel wordt de kennis over deze bijzondere bij samengevat en gespeculeerd over de oorzaken van de achteruitgang in Nederland.
    Keywords: Hymenoptera ; Apidae ; Andrena coitana ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 8
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.1
    Publication Date: 2018-12-13
    Description: In 2015 werd Kelisia monoceros voor het eerst in ons land verzameld bij Kamperland in Zeeland. Deze spoorcicade leeft op de algemeen voorkomende valse voszegge. De vondst wijst op een recente areaaluitbreiding. Een andere spoorcicade, Ditropsis flavipes, werd al eerder uit ons land gemeld, maar verspreidingsgegevens worden nu voor de eerste maal gepubliceerd. Ditropsis flavipes leeft monofaag op bergdravik, een in Nederland zeldzaam gras.
    Keywords: Homoptera ; Delphacidae ; Nederland ; verspreiding ; biologie ; Kelisia monoceros ; Ditropsis flavipes ; herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 9
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.17
    Publication Date: 2018-12-13
    Description: Alle spinnen hebben gif in hun kaken om hun prooien te doden. Verreweg de meeste soorten kunnen de menselijke huid niet doorboren met hun kaken en zijn dus volkomen ongevaarlijk. Kogelspinnen uit het genus Latrodectus, oftewel weduwen, vormen een uitzondering. Deze exotische spinnen worden af en toe geïmporteerd in Nederland. In 2013 is het aantal vondsten van geïmporteerde Latrodectus-spinnen op een rij gezet in een risicobeoordeling, met als resultaat een lijst van tien records met bewijsmateriaal. Hier kunnen nu vier records aan toegevoegd worden. Hieronder bevindt zich een vondst van de bruine weduwe L. geometricus, die recent voor het eerst in ons land werd vastgesteld, en een eerste geval van uitgekomen eitjes van een Latrodectus in ons land, van de roodrugspin L. hasselti.
    Keywords: Araneae ; Theridiidae ; Latrodectus ; Nederland ; exoot ; verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 10
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.27
    Publication Date: 2018-12-13
    Description: In 2015 werd tijdens een monitoringsproject van mariene bodemfauna op het Friese front de vulkaanworm Maxmuelleria lankesteri aangetroffen. Dit is de eerste vondst in Nederlandse wateren. De vulkaanworm dankt zijn naam aan de vorm van de opening van zijn leefgang, een vulkaanachtige slibheuvel. Het is opmerkelijk dat deze grote, opvallende worm (12-18 cm lang) niet eerder is aangetroffen. Mogelijk ligt dit aan de ongebruikelijke bemonsteringsmethode. Anderzijds kan de vulkaanworm daadwerkelijk zeldzaam zijn.
    Keywords: Echiura ; Maxmuelleria lankesteri ; Nederland ; verspreiding ; herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 11
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.95
    Publication Date: 2018-12-13
    Description: De kleine bleekvlekwespbij Nomada baccata behoort tot een complex van taxa rond de bleekvlekwespbij Nomada alboguttata. De kleine bleekvlekwespbij is vroeger verspreid over het land aangetroffen, maar de laatste waarneming dateerde alweer van 1992. In de afgelopen jaren werd de soort op twee plekken in ons land teruggevonden, in de Schoorlse duinen in Noord-Holland in 2012 en op de Tongerense hei bij Epe in Gelderland in 2015.
    Keywords: Hymenoptera ; Apidae ; Nomada baccata ; taxonomie ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 12
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.37
    Publication Date: 2018-12-13
    Description: De familie der sluipvliegen is één van de soortenrijkste vliegenfamilies in ons land. De larven ontwikkelen zich inwendig in ongewervelden, veelal vlinderrupsen. De groep is in ons land relatief goed bestudeerd en de afgelopen jaren zijn diverse aanvullingen op de checklist uit 2002 gepubliceerd. In dit artikel worden wederom twee soorten voor het eerst uit ons land vermeld. Hiermee komt het totaal aantal soorten dat in Nederland is vastgesteld op 336. Daarnaast wordt de herontdekking van een soort beschreven die al meer dan een eeuw niet meer waargenomen was.
    Keywords: Diptera ; Tachinidae ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 13
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.15
    Publication Date: 2018-12-13
    Description: Canacidae zijn gebonden aan de kust en zou je daarmee typisch Nederlandse vliegjes kunnen noemen. In dit artikel melden wij een nieuwe soort van deze familie: Canace nasica en presenteren we een nieuwe Nederlandse checklist voor de familie. Naar de nieuwste taxonomische inzichten wordt daarbij de familie Tethinidae als subfamilie onder de Canacidae toegevoegd. Hiermee is de Nederlandse fauna een vliegenfamilie armer.
    Keywords: Diptera ; Canacidae ; Canace nasica ; Nederland ; herkenning ; verspreiding ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 14
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.11
    Publication Date: 2018-12-13
    Description: De kassprinkhaan is een buitenbeentje onder de Nederlandse sprinkhanen en krekels. Ze komt van oorsprong waarschijnlijk voor in grotten in Oost-Azië en is door transport van eieren met plantenmateriaal over de hele wereld verspreid geraakt. Ze kan tijdelijk overleven in het kunstmatig grotmilieu van bijvoorbeeld kruipruimtes van woonhuizen, in kassen en tuincentra. Recentelijk werd een opmerkelijk grote populatie van de kassprinkhaan gevonden in het uitgebreide stelsel aan kruipruimtes onder een verpleeghuis in Friesland. De kassprinkhaan blijkt hier al ruim 40 jaar voor te komen. Het is waarschijnlijk de grootste Europese populatie van deze soort.
    Keywords: Orthoptera ; Diestrammena asynamora ; verspreiding ; exoot ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 15
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    In:  Nederlandse Faunistische Mededelingen (0196-2453) vol.46 (2016) p.43
    Publication Date: 2018-12-13
    Description: In het kader van het project ‘Duik de Noordzee Schoon’ worden scheepswrakken onderzocht, beschreven en van afval ontdaan. Scheepswrakken vormen een bijzonder leefgebied in het mariene milieu, met een hoge biodiversiteit. Dit bleek weer tijdens onderzoek van visnetten die van ver weg gelegen wrakken waren verwijderd. Hierbij werden maar liefst vier nieuwe mosdiertjes voor de Nederlandse fauna aangetroffen.
    Keywords: Bryozoa ; Nederland ; verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 16
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.43
    Publication Date: 2018-12-13
    Description: Pauropoda of weinigpoten zijn nauw verwant aan de miljoenpoten en duizendpoten. Het is een weinig bestudeerde diergroep, die bestaat uit kleine, witte en blinde bodemdieren die nauwelijks opvallen. Het meest kenmerkende zijn de gevorkte antennen, die wat bouw betreft uniek zijn ten opzichte van andere ongewervelden. Er zijn slechts acht soorten gemeld uit Nederland, alle behorend tot het genus Allopauropus. Recentelijk is een nieuwe soort, uit het genus Pauropus, in het westen van het land aangetroffen. Het betreft dus ook een nieuw genus voor de Nederlandse fauna. In dit artikel wordt de nieuwe soort voorgesteld, beschrijven we de habitat en geven we informatie over de verspreiding.
    Keywords: Myriapoda ; Pauropoda ; Pauropus lanceolatus ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 17
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.46 (2016) p.19
    Publication Date: 2018-12-13
    Description: Slakkendodende vliegen (familie Sciomyzidae) zijn al niet zo opvallend in het veld, maar de soorten uit de genera Pherbellia en Ditaeniella worden nog minder gevonden, mede doordat ze vrij klein zijn. De 14 Nederlandse soorten lijken sterk op elkaar. Dit artikel biedt een tabel om ze te kunnen herkennen en geeft informatie over ecologie en verspreiding.
    Keywords: Diptera ; Sciomyzidae ; Pherbellia ; Ditaeniella ; Nederland ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 18
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.1
    Publication Date: 2018-12-13
    Description: Platwormen komen in Nederland vooral voor in zoet water, maar er zijn twee soorten van landbiotoop bekend. De laatste jaren duiken steeds vaker exotische landplatwormen op in Europa, vooral in kassen en tuincentra, maar sommige kunnen ook buitenshuis overleven. Uit Nederland zijn Bipalium kewense, Caenoplana bicolor en Marionfyfea adventor gemeld. Omdat ze regenwormen en slakken eten, kunnen ze een grote invloed hebben op het bodemleven, met gevolgen voor natuurlijke ecosystemen en landbouwgebieden. In het buitenland is de aandacht voor exotische landplatwormen al groeiende. Zo wordt de Nieuw-Guineese landplatworm Platydemus manokwari door de IUCN tot de 100 ergste invasieve soorten aangemerkt. In Nederland is er nog nauwelijks aandacht voor landplatwormen. Daarom wordt in dit artikel de kennis over deze groep samengevat.
    Keywords: Platyhelminthes ; Tricladida ; Nederland ; verspreiding ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 19
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.39
    Publication Date: 2018-12-13
    Description: Blaaskopvliegen zijn een van de groepen uit het atlasproject Leuke vliegen, dat in 2015 werd afgesloten. Het zijn over het algemeen opvallend gekleurde vliegen, die parasiteren bij bijen en wespen. In een overzichtsartikel uit 2014 werd de komst van Leopoldius calceatus al voorspeld en in 2015 werd soort inderdaad aangetroffen in Groeve Craubeek in de provincie Limburg en een jaar later op de Stratumse heide bij Eindhoven.
    Keywords: Diptera ; Conopidae ; Nederland ; Leopoldius calceatus ; verspreiding ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 20
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.47 (2016) p.49
    Publication Date: 2018-12-13
    Description: Astigmatic mites probably form the most diverse cohort of mites. At present the former order of Astigmatina is ranked within the suborder Oribatida or moss mites. However astigmatic mites occupy a much wider range of habitats than other oribatid mites: from marine coasts to stored food, plant bulbs and houses. The vast majority live as commensals or parasites on a variety of hosts, ranging from insects to birds and mammals, inhabiting the fur, feathers, skin and even lungs and stomach. This first checklist for the Netherlands contains 262 species, but many more are to be expected. Brief data on occurrence and nomenclature are provided for each species.
    Keywords: Acari ; Oribatida ; Astigmatina ; verspreiding ; taxonomie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 21
    Publication Date: 2016-02-09
    Description: Wing shape variation was investigated between the sexes and among four populations of the scorpionfly Dicerapanorpa magna (Chou, 1981) endemic to the Qin-Ba Mountains area, China through the landmark-based geometric morphometric approach. The results show that sexual dimorphism exists both in wing size and shape in D. magna. Significant differences exist in female wing size and shape among D. magna populations. The possible reasons of the wing variation are discussed based on the divergence time of D. magna in combination with the tectonic and climatic events in the Qin-Ba Mountains during the late Miocene-Pleistocene period. Whether reproductive isolation exists between different populations needs further research.
    Keywords: canonical variates analysis ; individual variation ; sexual dimorphism ; 42.75 ; 42.62
    Repository Name: National Museum of Natural History, Netherlands
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  • 22
    Publication Date: 2017-12-07
    Description: In Nederland zijn natuurlijke en semi-natuurlijke graslanden relatief slecht onderzocht op de aanwezigheid van springstaarten. In de ons omringende landen zijn deze biotopen vaak rijk aan specifieke soorten die alleen daar voorkomen. Naar verwachting kunnen in dit milieu veel nieuwe soorten voor onze fauna gevonden worden, vooral op nutriëntarme, zandige en droge ondergrond. Recentelijk zijn twee soorten uit het genus Folsomides in graslanden in het zuiden van ons land aangetroffen. Het betreft hier een nieuw genus voor de Nederlandse fauna. In dit artikel worden het genus en de twee soorten voorgesteld, beschrijven we de habitat en geven we informatie over de verspreiding en begeleidende soorten van deze springstaarten.
    Keywords: Collembola ; Isotomidae ; Folsomides ; verspreiding ; Nederland ; herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 23
    Publication Date: 2017-12-07
    Description: Psilota is een genus van kleine, zwarte zweefvliegen, waarvan de larven leven achter boomschors. In 1988 werd Psilota anthracina voor het eerst in Nederland waargenomen en lange tijd is het een zeldzame soort geweest. De laatste jaren wordt ze steeds algemener, vermoedelijk door een veranderd bosbeheer. Gaandeweg is gebleken dat er een tweede soort onder schuilging; P. atra. Toen in België een derde soort opdook was het wachten tot deze ook in Nederland aangetroffen zou worden. In 2012 was het zover. Als Nederlandse naam stellen we voor spichtige spitsbek.
    Keywords: Diptera ; Syrphidae ; Psilota ; verspreiding ; Nederland ; herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 24
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.51
    Publication Date: 2017-12-07
    Description: Het voorkomen van Badonnelia titei in ons land wordt in enkele publicaties genoemd. Deze exoot blijkt niet zeldzaam in archiefdepots overal in Nederland. In deze publicaties werd echter geen aandacht besteed aan het feit dat de soort nog niet als nieuw voor Nederland was gemeld, waar bewijsexemplaren zijn ondergebracht en hoe B. titei te herkennen is. De soort is daarom dan ook nooit doorgedrongen tot de diverse faunaoverzichten van Nederlandse stofluizen. Reden genoeg om deze zaken te behandelen in dit artikel, waarbij tevens een vindplaatsenkaartje wordt gegeven en de eerste vondsten uit woonhuizen worden gemeld.
    Keywords: Psocodea ; Sphaeropsocidae ; Badonnelia titei ; verspreiding ; Nederland ; exoot ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 25
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.44 (2015) p.1
    Publication Date: 2017-12-07
    Description: De omgeving van Ommen en Hardenberg is het enige gebied in Nederland waar alle vier de soorten rode bosmieren voorkomen, waaronder de in Noordwest-Europa zeer zeldzame stronkmier. Recent is aan de alarmbel getrokken omdat het niet goed gaat met deze soort. Aanleiding voor een nieuw onderzoek bij Ommen, waarbij alle bosmieren onder de loep zijn genomen.
    Keywords: Hymenoptera ; Formicidae ; Formica ; verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 26
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    In:  Contributions to Zoology (1875-9866) vol.84 (2015) nr.4 p.305
    Publication Date: 2015-12-07
    Description: Firm coupling of genitalia is critical for copulation in most groups of insects. To counter female resistance that usually breaks off genital connection, male scorpionflies (Mecoptera: Panorpidae) usually provide nuptial gifts for the female and seize their mates with grasping devices. The notal organ, a modified clamp on tergum III of male scorpionflies, plays a significant role in seizing the female wings and helping maintain mating position during copulation. The mating behaviour remains unknown for the scorpionfly Furcatopanorpa longihypovalva (Hua and Cai, 2009) whose male lacks a notal organ. In this paper, we first attempt to study the mating behaviour of F. longihypovalva. The results show that the male provides liquid salivary secretion through a mouth-to-mouth mode for the female, and maintains copulation mainly by continuous provision of salivary secretion rather than by seizing the female with grasping devices. Thus the male copulates with the female in an atypical O-shaped position, with only their mouthparts and genitalia connected to each other. The salivary glands exhibit remarkable sexual dimorphism: short and bifurcated in the female, but well-developed and multi-furcated in the male. The extremely developed salivary glands of the male lay a structural foundation for the male to continuously provide liquid salivary secretion, and to help the male to mediate female resistance, being likely to serve as a compensation to his absence of the notal organ. We also investigated the functional morphology and copulatory mechanism of the male and female genitalia. The evolution of the atypical mating pattern of F. longihypovalva is putatively discussed as an adaptation in the context of sexual conflict.
    Keywords: Mecoptera ; Panorpidae ; Furcatopanorpa longihypovalva ; mating behaviour ; nuptial feeding, ; salivary glands ; genitalia ; functional morphology ; copulation ; 42.75 ; 42.62
    Repository Name: National Museum of Natural History, Netherlands
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  • 27
    Publication Date: 2015-11-10
    Description: Female genitalia are widely underrepresented in taxonomic studies. Here we investigate the morphological variation among female copulation organs for a group of scarab beetles (Sericini) with similar ecology, external morphology and copulation mechanics. We examined traits qualitatively and quantitatively based on 80 and 18 species (genus Pleophylla), respectively. Additionally we explored whether female genitalia are affected by asymmetry. The vast diversity of slerotised structures including their shapes illustrated the high taxonomic and phylogenetic utility of female genitalia in this group. The morphometric analysis of Pleophylla, confirmed that sclerotisations in the ductus bursae are very suitable for species-level taxonomic purposes. Stable interspecific variation is more hardly discernable in other parts such as the vaginal palps (shape and size) or the other membranous structures such as the shape of the bursa copulatrix. Asymmetric genitalia that arose multiple times independently among insects are found in most of the examined Sericini species. Asymmetries regarded either the bursa copulatrix, or both the bursa copulatrix and ductus bursae and comprised sclerotised and non-sclerotised structures being most common in modern Sericini. Here, highly asymmetric sclerotised structures are linked with strong asymmetry of the male copulation organs. Widespread asymmetry among megadiverse Sericini with a complex male-female genital asymmetry suggests that the shift to asymmetry is phylogenetically rather conserved. From the range of hypotheses, sexual selection seems to be the most reasonable to explain the evolution and stability of asymmetry in chafer genitalia.
    Keywords: beetles ; female genitalia ; integrative taxonomy ; Melolonthinae ; morphology ; 42.75 ; 42.64 ; 42.62
    Repository Name: National Museum of Natural History, Netherlands
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  • 28
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.39
    Publication Date: 2017-12-07
    Keywords: Coleoptera ; Brentidae ; Exapion ulicis ; verspreiding ; Nederland ; herkenning ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 29
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.44 (2015) p.11
    Publication Date: 2017-12-07
    Description: Eikelwormen zijn mariene wormen die een eigen klasse vormen, de Enteropneusta. In Nederland zijn het ook de enige vertegenwoordigers van de kraagdragers (fylum Hemichordata). Het zijn bijzondere dieren, die nauwer verwant zijn aan stekelhuidigen en gewervelde dieren dan aan gelede wormen. Het lichaam is ongeleed, met een gesteelde slurf, met daarachter een kraag en een langwerpig lichaam met tientallen kieuwspleten. De wormen leven in een U-vormige buis in zachte bodems. In de loop van de tijd zijn wel eikelwormen langs de Nederlandse kust verzameld, maar deze zijn nooit op naam gebracht. In dit artikel wordt ingegaan op de eerste vondsten van eikelwormen in de Oosterschelde.
    Keywords: Enteropneusta ; Saccoglossus ; verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 30
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.44 (2015) p.47
    Publication Date: 2017-12-07
    Description: The gall midges are one of the most important groups of gall makers. Emerging larvae produce stimuli and the host plant responds by producing galls, fascinating structures which provide food and shelter for the developing larvae. Most gall inducing midges are host specific: they are only able to induce galls in a few, often related, plant species. A few species have different feeding modes: among them are saprophagous, fungivorous and predaceous species and some are used in biocontrol. We recorded 416 species in the whole area; 366 species are recorded from the Netherlands, 270 species from Belgium and 96 species from Luxembourg.
    Keywords: Diptera ; Cecidomyiidae ; Netherlands ; Belgium ; Luxembourg ; distribution ; biology ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 31
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.19
    Publication Date: 2017-12-07
    Description: Het gebeurt met enige regelmaat dat er boorvliegen versleept worden met plantaardige producten. De meeste schadelijke soorten komen uit de tropen en kunnen zich niet handhaven in Nederland. Noord-Amerikaanse soorten van het genus Rhagoletis kunnen in het klimatologisch vergelijkbare Europa wel voet aan de grond krijgen. Eerder bleek dit al met de Oost-Amerikaanse kersenboorvlieg en nu staat hetzelfde te gebeuren met de walnootboorvlieg.
    Keywords: Diptera ; Tephritidae ; Rhagoletis completa ; verspreiding ; herkenning ; Nederland ; exoot ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 32
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.13
    Publication Date: 2017-12-07
    Description: Door gebruik te maken van observatiekunstnestjes is het mogelijk om regelmatig een kijkje te nemen in de nesten van bijvoorbeeld graafwespen. Zij gebruiken de nesten om zich voort te planten. Zo kunnen we meer te weten komen over hun gedrag in het nest tijdens de voortplanting. In dit artikel worden de ervaringen met de graafwesp Psenulus fuscipennis beschreven. De verschillen in levenswijze met de kleine zeefwesp en bijenwolf worden toegelicht.
    Keywords: Hymenoptera ; Crabronidae ; Psenulus fuscipennis ; biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 33
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.7
    Publication Date: 2017-12-07
    Description: De gele tubebij Stelis signata was sinds 1977 niet meer in ons land aangetroffen. Men dacht daarom dat deze bij uit ons land verdwenen was. In 2013 werd de soort echter op Waarneming.nl gemeld van de Strabrechtse hei en in 2014 van Afferden. In 2015 werd een vrouwtje gevangen op de Sprengenberg op de Sallandse heuvelrug. In 2011 heeft Natuurmonumenten hier kleinschalige maatregelen uitgevoerd voor specifieke heidesoorten, waaronder de aanleg van een flink aantal steilranden. Het microreliëf dat daarbij ontstaat vormt een belangrijke nestelplaats voor bijen en wespen. De vondst van de zeldzame gele tubebij op een van deze steilranden vormt de kroon op het werk.
    Keywords: Hymenoptera ; Megachilidae ; Stelis signata ; verspreiding ; biologie ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 34
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.44 (2015) p.37
    Publication Date: 2018-12-13
    Description: In 2007 werd Diplocoelus fagi bij Wageningen gevonden. De larven van deze kever leven in dood hout. Na de eerste vondst zijn diverse andere waarnemingen gedaan en D. fagi is nu bekend uit vier provincies. Omdat de soort in de omringende landen al lang bekend was, is deze late ontdekking opmerkelijk. Mogelijk hangt dit samen met het verbeterde bosbeheer, waarbij minder dood hout uit de bossen wordt verwijderd.
    Keywords: Coleoptera ; Biphyllidae ; Diplocoelus fagi ; verspreiding ; Nederland ; biologie ; herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 35
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    In:  Nederlandse Faunistische Mededelingen (42.75) vol.44 (2015) p.29
    Publication Date: 2017-12-07
    Description: The snail-killing fly Salticella fasciata was discovered in Belgium in 2010. Since then, several new localities on the Belgian coast were discovered and in 2014, the first record for the Netherlands was found. This is the first representative of the genus and also of the subfamily Salticellinae in the Netherlands. In this paper, records from Belgium and the Netherlands are reviewed and information on biology and habitats is summarised.
    Keywords: Diptera ; Sciomyziidae ; Salticella fasciata ; Nederland ; België ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 36
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.44 (2015) p.17
    Publication Date: 2017-12-07
    Description: Twaalf jaar geleden waren er nog geen Nelima-soorten bekend uit ons land. In 2004 en 2006 werden respectievelijk N. sempronii en N. doriae ontdekt. Beide soorten komen ten zuidoosten van ons land voor, en hebben naar alle waarschijnlijkheid Nederland recent bereikt. In 2012 werd op de Maasvlakte een derde vertegenwoordiger van dit genus gevonden: Nelima gothica. De vindplaats lijkt te wijzen op introductie door de mens. Gezien het voorkomen in de ons omringende landen is echter niet uit te sluiten dat hij van oudsher tot onze fauna behoort of recent op eigen kracht Nederland heeft bereikt. Hij zou op meer plaatsen langs de kust kunnen voorkomen. We presenteren de nieuwe soort en geven een overzicht van de vier Noordwest-Europese Nelima-soorten.
    Keywords: Opiliones ; Nelima ; verspreiding ; Nederland ; Europa ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 37
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.1
    Publication Date: 2018-12-13
    Description: Goudwespen zijn fraaie insecten, met felle metaalkleuren in de tinten rood, groen en blauw. Ze parasiteren vaak bij bijen en angeldragende wespen. In dit artikel wordt de eerste vondst van Chrysis equestris voor Nederland beschreven, waarmee het aantal in Nederland gevonden soorten nu op 57 komt. Deze goudwesp parasiteert bij de plooivleugelwesp Discoelius zonalis. Ze wordt in haar hele areaal weinig gevangen.
    Keywords: Hymenoptera ; Chrysididae ; Chrysis equestris ; verspreiding ; biologie ; herkenning ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 38
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.91
    Publication Date: 2017-12-07
    Description: The Flevopark is one of the most special green areas of Amsterdam with a rich nature. Twelve oribatid mite species were collected here in 2014 from bark and mosses on trees. Liacarus acutus and Perlohmannia dissimilis are reported for the first time from the Netherlands. It is not clear if the newly recorded species have always been overlooked or are recent immigrants.
    Keywords: Acari ; Oribatida ; distribution ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 39
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.77
    Publication Date: 2017-12-07
    Description: Watermijten zijn kleine spinachtige diertjes, die in zoet water leven. De aandacht voor deze diergroep is groot, omdat ze een rol spelen in de waterkwaliteitsbeoordeling. In de verspreidingsatlas uit 2000 worden 234 Nederlandse watermijten gemeld. Sinds die tijd worden regelmatig aanvullingen gerapporteerd. In dit artikel worden weer acht nieuwe soorten gemeld, wat het totaal nu op 266 brengt. Dit is een opmerkelijke toename van 13 % in 15 jaar.
    Keywords: Acari ; Hydrachnidia ; verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 40
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.67
    Publication Date: 2017-12-07
    Description: De publicatie van de naamlijst van de Nederlandse kieuwpootkreeften in 2002 was een grote stimulans voor nieuw onderzoek. Na de publicatie met aanvullingen in 2009 zijn er weer negen soorten bijgekomen, waarmee het totaal aantal soorten kieuwpootkreeften in Nederland nu op 124 komt. In dit artikel worden de nieuwe soorten besproken en wordt ingegaan op de redenen voor deze opmerkelijke uitbreiding.
    Keywords: Crustacea ; Branchiopoda ; Cladocera ; Nederland ; verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 41
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    In:  Nederlandse Faunistische Mededelingen (0169-2453) vol.45 (2015) p.33
    Publication Date: 2017-12-07
    Description: Prachtvliegen zijn vrij kleine vliegen die vaak een vleugeltekening hebben waardoor ze aan boorvliegen doen denken. De meeste soorten zijn weinig opvallend in het veld aanwezig en zitten vooral op hun waardplanten. Alleen de soorten waarvan de larven leven onder schors van boomstammen zijn opvallender aanwezig door hun balts of territoriaal gedrag. Ze proberen hun stukje boomstam te claimen door snel op en neer te lopen en tegelijkertijd driftig met hun vleugels te bewegen. Tot nog toe was de zeer fraaie Myennis octopunctata (Coquebert, 1798) de enige houtbewonende prachtvlieg in Nederland. In dit artikel wordt daar Homalocephala biumbrata aan toegevoegd.
    Keywords: Diptera ; Ulidiidae ; Homalocephala biumbrata ; verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 42
    Publication Date: 2015-11-07
    Description: Integrative taxonomy tests the validity of taxa using methods additional to traditional morphology. The existence of two different morphotypes in specimens identified as Chrysotoxum vernale Loew (Diptera: Syrphidae) prompted their taxonomic study using an integrative approach that included morphology, wing and male-surstylus geometric morphometrics, genetic and ecological analyses. As a result, a new species is recognised, Chrysotoxum montanum Nedeljković & Vujić sp. nov., and C. vernale is re-defined. A lectotype and paralectotypes are designated for C. vernale to stabilize this concept. An additional species, Chrysotoxum orthostylum Vujić sp. nov., with distinctive male genitalia is also described. The three species share an antenna with the basoflagellomere shorter than the scape plus pedicel and terga with yellow fasciae not reaching the lateral margins. This study confirms the value of integrative approach for resolving species boundaries.
    Keywords: Balkan Peninsula ; C. montanum sp. nov. ; C. orthostylum sp. nov. ; ecological niche ; geometric morphometry ; lectotype ; mtDNA COI sequences ; Syrphinae ; 42.75 ; 42.64 ; 42.62
    Repository Name: National Museum of Natural History, Netherlands
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  • 43
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1-27 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a method for determining chemical kinetic constants and diffusion coefficients by measuring the rates of decay of spontaneous concentration fluctuations. The equilibrium of the system is not disturbed during the measurement. We measure the number of molecules of a specified type in a defined open volume as a function of time and compute the time course of the deviations from the thermodynamic mean concentration. The method is based on the principle that the rates of decay of spontaneous microscopic fluctuations are determined by the same phenomenological rate coefficients as those of macroscopic departures from equilibrium which result from external perturbations. Hence, an analysis of fluctuations yields the same chemical rate constants and diffusion coefficients as are measured by conventional procedures. In practice the number of the specified molecules is measured by a property such as absorbance or fluorescence which is specific and sensitive to chemical change. The sample volume is defined by a light beam which traverses the cell. As the molecules appear in or disappear from the light beam, either due to diffusion or chemical reaction, their concentration fluctuations give rise to corresponding fluctuations of the intensity of absorbed or emitted light. This paper presents the theory needed to derive chemical rate constants and diffusion coefficients from these fluctuations in light intensity. The theory is applied to three examples of general interest: pure diffusion in the absence of chemical reaction; the binding of a small rapidly diffusing ligand to a larger slowly diffusing macromolecule; and a unimolecular isomerization. The method should be especially useful in studying highly cooperative systems, relatively noncooperative systems with intermediate states closely spaced in free energy, small systems, and systems not readily subject to perturbations of state.
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  • 44
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 97-114 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular conformations and dynamics of poly(L-prolyl), poly(hydroxyl-L-prolyl), poly(L-prolyl-glycyl), poly(hydroxyl-L-prolyl), and poly(glycyl-glycyl-L-prolyl-glycyl), in aqueous solution, have been studied using 13C pulse Fourier transform nmr spectroscopy. From a measurement of the intensities of major and minor resonances in the spectra of the copolypeptides, it was determined that 15-20% of the glycyl-prolyl and glycyl-hydroxyprolyl peptide bonds are cis. Effective rotational correlation times (τeff), obtained from measurements of spin-lattice relaxation times (T1) of individual backbone and side-chain carbons, demonstrated that backbone reorientation is approximately isotropic for the five polypeptides and is characterized by correlation times of ca. 0.3-0.6 nanoseconds as a result of rapid segmental motion. In a given polypeptide glycyl and pyrrolidine residues were found to have the same backbone correlation times, but backbone carbon τeff values did decrease as the glycyl content of the peptides increased. A semi-quantitative analysis of Cβ, Cγ, and Cδ correlation times suggests that rapid ring motion in both prolyl and hydroxyprolyl involves primarily Cγ and Cβ, with the prolyl ring being more mobile than the hydroxyprolyl ring.
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  • 45
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 237-238 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No. Abstract.
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  • 46
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 217-226 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A model for the flexibility of DNA is proposed that is based on discrete variations in the direction of propagation in going from one subunit to the next. Expansion of the local free energy in terms of the local bending gives a Gaussian distribution function. The assumption of the independence of local bends on neighbors lead to very simple formulae for the persistence length and the characteristic ratio. Emphasis, however, is placed on the application of the formulae for molecules of finite size where the persistence length and C∞ are not defined. The formulae are worked out for two models, which should serve as limits for the real physical situation.
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  • 47
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 735-743 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If dispersion effects are not taken into account, the dimensions of particles in suspension estimated from spectrophotometric data (slope of the log OD versus log λ plot) are too low. By measuring dispersion curves for the medium and for the suspension, a consistent estimate of the size of latex particles of different diameter is obtained from the OD data.
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  • 48
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 765-768 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transition of poly-N5-(3-hydroxypropyl)-L-glutamine in methanol-water solutions has been observed using 13C nuclear magnetic resonance. Two signals appear in the α-CH region in the course of the transition; this is in contrast with previous proton magnetic resonance experiments carried out on this polymer in the same solvent system.
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  • 49
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 779-790 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray diffraction and stereochemical analyses were used to study the hydrated structure of the helical amylose polymorph having a fiber repeat spacing of 8 Å. Intensity calculations using computer models confirmed six as the number of residues per turn and supported the space group P212121. Both diffraction intensity and stereochemical methods indicate the suitability of residue G3 from the potassium acetate complex of cyclohexaamylose as opposed to residues with longer O(4)-O(1) vectors. Comparison of the present results with those obtained for V amylose dehydrate indicated no major conformational differences between the two helix skeletons. A net helical rotation of approximately 30° accompanied the hydrate-dehydrate transition and the rotational position in the hydrate allowed packing that was less close. Hydration water molecules were not located; noncarbohydrate peaks on the electron density maps were primarily due to Fourier series termination errors.
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  • 50
    Electronic Resource
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    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 843-852 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have measured the circular dichroism spectra and have obtained melting curves for samples of purified satellite DNA's from three species of crab, Cancer borealis, Gecarcinus lateralis, and Callinectes sapidus. Although all three satellite DNA's have the same density in neutral CsCl, their circular dichroism spectra and melting and reassociation characteristics are different, as are other properties of these DNA's. The circular dichroism spectra are analyzed to give estimates of nearest-neighbor frequencies. We estimate that about 90% of the Cancer borealis satellite DNA and over 80% of the Gecarcinus lateralis satellite DNA consist of d(AT)n:d(AT)n sequences, while the serially repeating unit of the Callinectes sapidus satellite DNA may not contain any extended d(AT)n:d(AT)n sequences. The results from the circular dichroism spectra for the Cancer borealis, Gecarcinus lateralis, and the Callinectes sapidus satellite DNA's are in agreement with base composition analyses, which give 2.4, 8, and 25% G+C, respectively, for these DNA's.
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  • 51
    Electronic Resource
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    Biopolymers 13 (1974), S. 879-890 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Samples of epichlorohydrin crosslinked potato starch were prepared by using a high ratio of starch to water and alkali concentration below the gelatinization level. This yielded crosslinked samples that were partially crystalline, and where the number of crosslinks could be varied between 1 and 20 crosslinks per 100 anhydroglucose units. The degree of swelling varied regularly with degree of crosslinking, and the molecular weight between crosslinks Mc as derived from swelling data in a good swelling agent compared favorably with Mc derived from chemical analysis.From the heat of gelatinization of the crosslinked starches, as observed in a differential scanning calorimeter, for gelatinization in glycerol, water, and dimethylsulfoxide, a model for the gel state of the crosslinked starch is proposed. It is concluded that the entropy of melting is the determining factor in establishing the temperature of gelatinization.
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    Biopolymers 13 (1974), S. 909-917 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism studies of the interaction of β-cyclodextrin with a series of eight dinucleoside phosphates, and with 3′-AMP are reported. From results with ApU and ApA, it is shown that β-cyclodextrin binding is sensitive to dinucleoside stacking in approximately the same way as optical measures of stacking. Some qualitative uses of β-cyclodextrin binding are suggested, based on the fact that the change in the CD spectrum caused by cyclodextrin binding is unique to each of the dinucleosides studied. Hoffman and Bock have previously suggested the use of β-cyclodextrin as a probe of nucleic acid structure. Their work indicated that only binding to adenosine and inosine would have to be considered. The present paper shows that binding to other bases cannot be neglected, and will impose serious restrictions on the use of β-cyclodextrin as a structural probe.
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    Biopolymers 13 (1974), S. 987-993 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(1,N6-etheno-2-aza-adenylic acid) [poly(2-aza-εA)] was synthesized from 1,N6-etheno-2-aza-adenosine 5′-diphosphate (2-aza-εADP) and Escherichia coli polynucleotide phosphorylase. The values Km = 1.02 mM, V = 1.06 μmol hr-1 enzyme unit-1 were found for the polymerization reaction. In contrast to polyadenylic acid, this novel fluorescent polymer has a random structure in solution. The application of the 2-aza-εADP for localization of polynucleotide phosphorylase was also described.
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    Biopolymers 13 (1974), S. 1011-1022 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of L-methionine oligomers [BOC-(Met)n-OMe] (n = 2-7) and the corresponding diastereomeric di- and tripeptides were synthesized using the mixed anhydride method. Oligomers prepared in this manner were optically pure and were obtained in reasonable yield. Preliminary optical examination of the peptides suggests that secondary structures may begin forming in the pentamer or hexamer in trifluoroethanol. BOC-(Met)4-OMe and BOC-(Met)5-OMe were also synthesized using an insoluble resin containing BOC-L-methionine as the nitrophenol active ester.
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    Notes: Conformational studies of a series of oligopeptides (from the tripeptide to the octadecapeptide) with the repeating sequence L-norvalyl-glycyl-L-proline and a polytripeptide with this sequence are reported. By means of chiroptical techniques, unordered conformations are found for all oligopeptides in water, trifluoroethanol, and ethylene glycol and for the water-insoluble polymer in trifluoroethanol. In ethylene glycol the polymer assumes a collagen-like structure. Infrared studies indicate that all the oligomers, in contrast to the polymer, are unordered in the solid state.
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    Biopolymers 13 (1974), S. 1109-1116 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Uncharged poly(Nε-methyl-L-lysine) (PMLL) and its isomer, poly(Nδ-ethyl-L-ornithine) (PELO), in alkaline solution (pH ca. 12) undergo a helix-to-β transition upon mild heating at 50°C or higher in a manner similar to that of poly(L-lysine) (PLL). The rate of conversion follows the order: PMLL 〈 PELO 〈 PLL. The helix can be regenerated upon cooling near zero degrees, for instance, after more than 12 hr at 2°C. At concentrations less than 0.02% the β form is intramolecular, but at higher concentrations both intra- and intermolecular β forms are generated. Poly(Nδ-methyl-L-ornithine) (PMLO), an isomer of PLL, behaves like poly(L-ornithine); uncharged PMLO in alkaline solution is partially helical and becomes disordered at elevated temperatures.
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    Biopolymers 13 (1974), S. 1161-1171 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study the effect of side-chain length on the conformation of polypeptides, conformational changes of various ionic polypeptides with various lengths of side chain, poly-Nε-glutaryl-L-lysine (PGL), poly-Nδ-glutaryl-L-ornithine (PGO), poly-Nε-succinyl-L-lysine (PSL), and poly-Nδ-succinyl-L-ornithine (PGO), were investigated by ORD, potentiometric titration, and dilatometric measurements in aqueous solution. The results of optical rotation and potentiometric titration measurements indicate strongly that the α-helix stability increases in the sequence PSO 〈 PSL ∼ PGO 〈 PGL, which corresponds to increased side-chain length. The volume change associated with the helix-coil transition also increased in the above sequence. This series of polymers seems to be more hydrophobic compared with poly-L-glutamic acid or poly-L-lysine, as suggested from the values of enthalpy and entropy changes for coil-helix transitions.
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    Biopolymers 13 (1974), S. 1195-1203 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational changes of poly-Nε-glutaryl-L-lysine (PGL) and poly-Nε-succinyl-L-lysine (PSL) in various salt solutions were studied by use of ORD and potentiometric titration measurements. The addition of alkali metal salts to the fully ionized PGL or PSL solution caused helix formation. The helical content of the polymers increases in the following sequences: at salt concentration 0-2 M, CsCl 〈 KCl 〈 LiCl 〈 NaCl; and at 2-3 M, LiCl 〈 CsCl 〈 KCl ∼ NaCl. The preferential binding of the solvent components with various alkali metal salts of PGL or PSL was measured in LiCl, NaCl, and KCl solutions by means of equilibrium dialysis and differential refractometry. It was found that with increasing salt concentration, the polymers were preferentially hydrated in NaCl and KCl soultions; however the salt was preferentially bound to the polymers in LiCl solution. Such preferential binding was suggested to be closely related to conformational change. The addition of CaCl2 to polymer solutions led to the stabilization of the helical structure of PGL or PSL.
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    Biopolymers 13 (1974), S. 1261-1267 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Refractive indices of bovine serum albumin solutions in saline and in 2-chloro ethanol are measured for the spectral region 1770-10000 Å by a reflectance method. A procedure for the determination of a dispersion formula for binary mixtures is developed and applied. The electronic polarizability of bovine serum albumin is determined and is found to be almost independent of the solvent and concentration. Hence it follows that the electronic polarizability of bovine serum albumin is almost independent of the molecular environment.
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    Biopolymers 13 (1974) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 61
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The dielectric absorption of poly-DL-phenylalanine and poly-γ-benzyl-L-aspartate (PLAB) was measured in very dilute solutions to determine the type of molecular association and to locate the helix-coil transition. Both polypeptides were present as associated helices in chloroform. The mode of aggregation, which was determined by measuring the dipole moment and the critical frequency, did not depend on the polarity of the side chain but rather on that of the solvent.In both polymers, the dissociation of the aggregates in chloroform was observed on addition of small amounts of dichloroacetic acid; further addition of the acid lead to the helix-coil transition.No second region of dielectric absorption that might be related to the kinetics of the transition was found during the helix-coil transition of PBLA.
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    Topics: Chemistry and Pharmacology
    Notes: Molecular conformation of some polysaccharides in aqueous solution in evidenced by changes in the optical rotation and in the elution pattern of gel filtration. The changes in the specific rotation against that in water are expressed as a molar conformational value [K]D21: -495° for colominic acid in 1.0 N NaOH solution, and -180° for hyaluronate (HA), +85° for corneal keratin sulfate, and +234° for amylose in 8 M urea solution. The gel filtration of amylose and HA dissolved in 8 M urea solution shows elution patterns distinctly different from those dissolved in water. The phenomena are attributable to a molecular conformational transition of polysaccharide molecules in aqueous solution.
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    Topics: Chemistry and Pharmacology
    Notes: A previously described procedure for simultaneous optimization of bond lengths and angles was used to test different models for mannan I. Potential hydrogen bonds and the glycosidic angle were included in the optimization. A conformational model with bifurcated intramolecular hydrogen bonds of the type observed in the methyl cellobioside methanol complex showed the best agreement with available exprerimental data. The coordinates of this model were provided by computer calculations. The available X-ray data, however, were not sufficient for selecting this model; rather, ir data were necessary to furnish the needed information. The different conformational models tested all showed an almost constant virtual bond length O(1)-O(4) of the β-pyranose residue. This was in contrast to the previously obtained results for the α-pyranose residues.
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    Biopolymers 13 (1974), S. 1187-1193 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The longitudinal proton magnetic relaxation times T1 were measured for ferri (met)-and carbonmonoxy-bovine haemoglobin and equine myoglobin in 0.1 M KH2PO4 aqueous solutions near pH 6 at 5°C and 35°C from 1.5- to 60-MHz Larmor frequencies. It is concluded that the correlation time τC for the dipole-dipole interaction of electron and nuclear spins is in fact the electron (ferric) spin relaxation time τS being close to 1.5 × 10-10 sec for both metHb and metMb at 5°C. At 35°C the paramagnetic relaxation rates are not determined solely by the relaxation of protons exchanging from the haem pocket with bulk solvent. Hence, τC at 35°C cannot be calculated from the dispersion data obtained at this temperature. The relevance of this for the determination of interspin distances r is discussed.
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    Biopolymers 13 (1974), S. 1213-1222 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The orientation of naphthalene rings in the side chain of poly-γ-1-naphthylmethyl-L-glutamate (PNLG) in mixed solvents of dichoroethane (DCE) and hexafluoroisopropanol (HFIP) has been studied together with its conformation by infrared, circular dichroism, and fluorescence spectra. The CD pattern of PNLG varies with the solvent composition while it maintains the α-helical conformation. The fluorescence spectra of PNLG in solution show excimer emission of the naphthalene chromophores. The ratio of intensity of the excimer emission to that of the normal fluorescence decreases as the HFIP component in the solvent increases. It is suggested that the naphthalene rings in the side chain of α-helical PNLG are more rigidly orientated in the solvents of higher HFIP ratio.
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    Biopolymers 13 (1974), S. 1269-1290 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The near ultraviolet chiroptical properties of L-cystine conformational isomers are examined on a static, “one-electron” model in which the disulfide moiety is the chromophoric group and the atoms of the L-alanyl fragments are treated as perturbers. The zeroth order chromophoric wave functions are calculated on a semiempirical molecular orbital model in which excited states are constructed in the virtual orbital-configuration interaction approximation. The perturbing environment is represented by point charges located at the atomic centers of the L-alanyl fragments. Chromophore-perturber interactions are expressed as charge-multipole moments with only the charge-dipole and charged-quadrupole terms being retained in the calculations. Vicinal contributions to the rotatory strengths of the five lowest energy disulfide transitions are computed for 30 conformational isomers of the L-cystine dizwitterion. The results provide support for the view that vicinal or peripheral effects can account entirely for the observed near ultraviolet (λ 〉 230 nm) chiroptical properties of L-cystine and its derivatives and that these properties are diagnostic of conformational features external to the disulfide moiety.
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    Topics: Chemistry and Pharmacology
    Notes: The circular dichroic spectrum of poly(Tyr,TyrBr) in trimethylphosphate from 180 to 320 nm is found to be a linear function of composition from 25 to 68% TyrBr, and the spectra of the Tyr and TyrBr components are resolved. For Tyr the resolved spectrum is in agreement with available CD spectra of poly(Tyr). These results are interpreted to mean that the side-chain conformations of Tyr and TyrBr are not affected by the other component, and that for Tyr the conformation is the same as in poly(Tyr). It is also concluded that poly(Tyr,TyrBr) is helical with the same helix sense as poly(Tyr). The restrictions on the side-chain conformations are discussed, and it is suggested that the Tyr and TyrBr side chains are all in the same χ1 region.
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    Biopolymers 13 (1974), S. 1377-1389 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of double-helical nucleic acids was calculated as a function of geometry using the theory of Tinoco and Johnson. This theory does not include contributions of near ultraviolet transitions that are not π → π* in nature. The calculated circular dichroism shows a strong dependence on the distance of base pairs from the helix axis and the tilt of the base pair. Smaller dependences are predicted for the propeller-like twist of a base pair and for variation of the angular increment per base pair. Moderately good agreement between calculated and many experimentally observed spectra could be generated.
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    Biopolymers 13 (1974), S. 1427-1434 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The maximum at 220 nm in the circular dichroism spectrum of native collagen solution changed to a negative value after heat denaturation or collagenase hydrolysis. The enzyme induced rate of CD change at 220 nm was shown to be first order in collagen concentration. The specific rate constant k is actually a combined rate constant kfast and kslow in which the ratio kf/ks is 4.1. The initial rates were linear with respect to enzyme concentration, and the Km was found to be 5.5 × 10-7 M. The rate of ultraviolet hyperchromicity at 220 nm on collagen hydrolysis was determined. The kfast was the same as that obtained by CD. The kf/ks ratio was 4.6. Both methods may be readily used to assay for collagenase activity.
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    Biopolymers 13 (1974), S. 1461-1482 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal and molecular structure of the complex of amylose with dimethyl sulfoxide has been studied by a combination of stereochemical analysis, potential energy, and X-ray diffraction methods. The complex crystallizes in a pseudotetragonal unit cell with a = b = 19.17 Å and c (fiber axis) = 24.39 Å, with two antiparallel chains per unit cell and space group P212121. The amylose chain is a left-handed 61(1.355) helix with three turns per crystallographic repeat. The O(6) rotational position is approximately gt. Dimethyl sulfoxide is located inside the helix with one DMSO molecule for every three glucose residues. An additional four DMSO molecules and eight water molecules each are located in the large interstices between chains, and it is the interaction of these molecules with the helix that results in the pseudotetragonal chain packing. The interstitial DMSO is the source of the previously reported additional layer lines, which are not consistent with the 8.13-Å amylose repeat distance. The final R factor for the layers with amylose contribution to the structure factors was 0.29, while the overall R factor was 0.35. The stereochemical packing analysis provided suitable phasing models for the subsequent X-ray refinement.
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    Biopolymers 13 (1974), S. 1549-1556 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric dispersion of DNA was studied in the frequency range 100 Hz-100 kHz at four different temperatures (6-30°C). The dielectric increment ε0-ε∞ increased with the rise of temperature. The relaxation time, on the other hand, decreased. Both the increase in dielectric increment and the decrease in relaxation time could not be explained on the basis of the counterion polarization theory. Dipole moment was estimated from Kirkwood theory. It was found to decrease systematically with temperature. Even at 0°C there was a dipole moment of 104D.
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    Biopolymers 13 (1974), S. 1573-1605 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of Förster long-range resonance energy transfer efficiency on the orientational freedom of donor D and acceptor A molecules attached to a macromolecular substrate is examined. The usefulness of polarized emission measurements in determining the mutual orientation as well as the degree of orientational freedom of D and A and thereby deriving maximum and minimum values for the D-A separation from the transfer efficieny is demonstrated.
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    Biopolymers 13 (1974), S. 1653-1659 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five human hemoglobins whose genetic relationship to one another involves one set of alleles, hemoglobins CC, SC, SS, AS, and AA, were studied in the deoxygenated form within a McBain gravimetric sorption system at 28°C. Water was used as the adsorbate at relative vapor pressures ranging from 0.11 to 0.39. The results of this study are reported and compared with a similar study on the ferric form of these same five hemoglobins. For both forms of hemoglobin studied, a slight increase was measured in the number of polar sites accessible to H2O vapor for those genotypes in which the substituent in the sixth position from the N terminus of the two β chains had a positively charged side chain, i.e., hemoglobin C. Those samples containing hemoglobin S (less soluble in the deoxy form) show an increased BET monolayer coverage in the deoxy as compared to the ferric form. For each genotype, the deoxygenated form had more polar sites accessible to H2O vapor than its ferric form. This finding is in agreement with an increase in the size of the central cavity as shown by crystallographic analysis.
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    Topics: Chemistry and Pharmacology
    Notes: Thermal denaturation of direct-mixed and reconstituted polylysine-DNA complexes in 2.5 × 10-4 M EDTA, pH 8.0 and various concentrations of NaCl has been studied. For both complexes, increasing ionic strength of the solution raises Tm, the melting temperature of free base pairs. The linear dependence of Tm on log Na+ indicates that the concept of electrostatic shielding on phosphate lattice of an infinitely long pure DNA by Na+ can be applied to short free DNA segments in a nucleoprotein. For a direct-mixed polylysine-DNA complex, the melting temperature of bound base pairs Tm′ remains constant at various ionic strengths. On the other hand, the Tm′ in a reconstituted polylysine-DNA complex is shifted to lower temperature at higher ionic strength. This phenomenon occurs for reconstituted complex with long polylysine of one thousand residues or short polylysine of one hundred residues. It is shown that such a decrease of Tm′ is not due to a reduction of coupling melting between free and bound regions in a complex when the ionic strength is raised. It is also not due to intermolecular or intramolecular change from a reconstituted to a direct-mixed complex. It is suggested that this phenomenon is due to structural change on polylysine-bound regions by ionic strength. It is suggested further that Na+ may replace water molecules and bind polylysine-bound regions in a reconstituted complex. Such a dehydration effect destabilizes these regions and lowers Tm′. This explanation is supported by circular dichroism (CD) results.
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    Topics: Chemistry and Pharmacology
    Notes: Theoretical values are reported for the specific conductivity, charge carrier mobilities, and delocalized free paths in β-polyglycine using the parallel-chain pleated sheet conformation and the all-valence electron energy band structure obtained previously. The mobilities are found to be much larger along the polypeptide backbones than in the direction of the hydrogen bonds. This indicates a mechanism of conduction in which the former path is favored for electronic delocalization. The preexponential factor of the specific conductivity obtained theoretically agrees well with experimental results.
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    Biopolymers 13 (1974), S. 1747-1750 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of a series of L-methionine oligopeptides [BOC-(Met)n-OMe] was examined in trifluoroethanol and hexafluoroacetone sesquihydrate. The results indicate that the trimer through the hexamer exists predominantly in disordered conformations in these solvents. An abrupt change in the CD pattern at the heptamer in trifluoroethanol suggests that L-methionine oligopeptides begin forming helices at this chain length.
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    Biopolymers 13 (1974), S. 1767-1776 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spin-lattice relaxation time (T1) of water adsorbed on collagen fibers was determined at six frequencies and temperatures varying from 25° to -80°C. Care was taken to eliminate the contributions to the signal of protons other than those in the adsorbed water. Quantitative calculations were made on T1 and the results were compared with the experimental data. It is suggested that a maximum of about 0.50-0.55 g water per g collagen forms a hydration layer, which cannot be frozen down to -90°C and exhibits a distribution of motional correlation times. For collagen samples containing a larger quantity of adsorbed water, the additional water molecules behave like ordinary isotropic water, having a single correlation time and a freezing temperature of about -10°C.
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    Biopolymers 13 (1974), S. 1821-1845 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser Raman spectra of the trinucleoside diphoshate ApApA and dinucleoside phosphates ApU, UpA, GpC, CpG, and GpU are reported and discussed. Assignments of conformationally sensitive frequencies are-facilitated by comparison with spectra reported here of poly(rA), poly(rC), and poly(rU) in deuterium oxide solutions. The significant spectral differences between ApU and UpA, and between GpC and CpG, reveal that the sequence isomers have nonidentical conformations in aqueous solution. In UpA at low temperature the bases are stacked and the backbone conformation is similar to that found in ordered polynucleotide structures and RNA. In ApU no base stacking can be detected and the backbone conformation differs from that found in UpA, both in the orientation of phosphodiester linkages and in the internal conformation of ribose. At the conditions employed neither ApU nor UpA exhibits base pairing in aqueous solutions. In both GpC and CpG the bases are stacked and the phosphodiester conformations are similar to those encountered for UpA and RNA. However, major differences between spectra of GpC and CpG indicate that the geometries of stacking and ribosyl conformations are different. In GpC the Raman data favor the formation of hydrogen bonded dimers containing GC pairs. Protonation of C in GpC is sufficient to eliminate the ordered conformation detected by Raman spectroscopy. Despite the ordered backbone conformation evident in GpU, this dinucleoside apparently contains neither stacked nor hydrogen bonded bases at the conditions employed here. The Raman data also confirm the stacking interactions in ApApA, poly(rA), and poly(rC) but suggest that the backbone conformation in poly(rC) differs qualitatively from that found in most ordered polynucleotide structures and is thermally more stable. The present results demonstrate the sensitivity of the Raman technique to sequence-related structural differences in oligonucleotides and provide additional spectra-structure correlations for future conformational studies of RNA by laser Raman spectroscopy.
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  • 79
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    Biopolymers 13 (1974) 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 80
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 300-MHz proton nmr spectra (between 11 and 14 ppm) of a series of double-stranded deoxy oligonucleotides of known sequence have been recorded in H2O solution. These resonances have been assigned to the G—N1H and T—N3H protons of specific base pairs from an evaluation of the temperature dependence of the ring NH linewidths and from the selective ring NH chemical shift changes on actinomycin-D binding. The deoxy oligonucleotides exist predominantly in the DNA-B conformation as evaluated from antibiotic binding studies. Ring-current calculations have been utilized to evaluate the up-field shifts of the G—N1H and T—N3H protons in Watson-Crick base pairs due to the ring currents from the pyrimidine and purine rings of nearest neighbor base pairs in regular DNA-B- and RNA-A-type helices. The perturbations on these up-field ring-current contributions that arise from twisting and tilting a base pair adjacent to the ring NH under study have been evaluated and found to change the calculated chemical shift by ±0.6 ppm for twist and tilt distortions of 〈30°C in a single adjacent base pair. A knowledge of the experimentally assigned ring NH chemical shifts of specific base pairs in known sequences of double-stranded deoxy oligonucleotides coupled with the ring-current tables for the DNA-B helical structure permit the assignment of 13.6 ± 0.1 ppm and 14.6 ± 0.2 ppm for the G—N1H proton of an isolated GC base pair and the T—N3H proton of an isolated AT base pair, respectively.
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  • 81
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    Biopolymers 13 (1974), S. 29-61 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the first experimental application of fluorescence correlation spectroscopy, a new method for determining chemical kinetic constants and diffusion coefficients. These quantities are measured by observing the time behaviour of the tiny concentration fluctuations which occur spontaneously in the reaction system even when it is in equilibrium. The equilibrium of the system is not disturbed during the experiment. The diffusion coefficients and chemical rate constants which determine the average time behaviour of these spontaneous fluctuations are the same as those sought by more conventional methods including temperature-jump or other perturbation techniques. The experiment consists essentially in measuring the variation with time of the number of molecules of specified reactants in a defined open volume of solution. The concentration of a reactant is measured by its fluorescence; the sample volume is defined by a focused laser beam which excites the fluorescence. The fluorescent emission fluctuates in proportion with the changes in the number of fluorescent molecules as they diffuse into and out of the sample volume and as they are created or eliminated by the chemical reactions. The number of these reactant molecules must be small to permit detection of the concentration fluctuations. Hence the sample volume is small (10-8 ml) and the concentration of the solutes is low (∼ 10-9 M). We have applied this technique to the study of two prototype systems: the simple example of pure diffusion of a single fluorescent species, rhodamine 6G, and the more interesting but more challenging example of the reaction of macromolecular DNA with the drug ethidium bromide to form a fluorescent complex. The increase of the fluorescence of the ethidium bromide upon formation of the complex permits the observation of the decay of concentration fluctuations via the chemical reaction and consequently the determination of chemical rate constants.
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  • 82
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    Biopolymers 13 (1974), S. 129-138 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The D and L copolymerizations of N-carboxy γ-benzyl glutamate anhydride (NCA) were carried out in a homogeneous solution with various D/L ratios, initiated by either n-butylamine or sodium methoxide, and were followed directly by circular dichroism (CD) to observe the behavior of the secondary structure of growing polymer molecules. In the n-butylamine system, the difference of the helical content between the righthanded and the lefthanded (Δα-helix) gradually increased as the polymerization proceeded, while in the sodium methoxide system, the Δα-helix had a tendency to decrease during the later stages of the polymerization. These results suggest a difference of the power of stereo-selection of monomer antipodes by the growing chain end between these systems, the stereoselectivity by the growing chain end in the sodium methoxide system being higher than that in the n-butylamine system.
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  • 83
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    Biopolymers 13 (1974), S. 169-183 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of Ac-Ala-NHMe, cyclo(-Ala-Ala-), Ac-Ala-OMe, Ac-Ala-Ala-OMe, and Ac-Ala-Ala-Ala-OMe has been measured in water and in aqueous salt solutions as a function of temperature. Only cyclo(-Ala-Ala-) exhibits circular dichroism which is independent of temperature. Each of the linear derivatives of L-alanine exhibits a positive circular dichroism in the range 208-218 nm at 15°C in water. Heating reduces the intensity of the positive circular dichroism, and only Ac-Ala-OMe retains positive circular dichroism at 75°C in water. Isothermal addition of salts produces changes in the circular dichroism of linear derivatives of L-alanine which resemble those seen on heating. The relative effectiveness of the salts tested, at a concentration of 4M, is LiCl ≤ KCl = NaCl 〈 MgCl2 ≤ CaCl2 ≤ NaClO4. The circular dichroism of cyclo(-Ala-Ala-) is also affected by the salts. Extrapolation of the results obtained with Ac-Ala-OMe, Ac-Ala-Ala-OMe, and Ac-Ala-Ala-Ala-OMe to a long polypeptide with a -CH2R side chain in the L-configuration leads to the conclusion that this polypeptide should exhibit a temperature-dependent salt-sensitive positive circular dichroism between 208 and 218 nm when it exists as a statstical coil.
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  • 84
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    Biopolymers 13 (1974), S. 227-235 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heats of the conformational conversion ΔHc of polyuridylic acid (polyU) in the presence of various cations were determined using a differential scanning microcalorimeter and an isothermal mixing calorimeter. The first method yields a value of ΔHc = 5.2 kcal/mol of base pairs, the second one a value of ΔHc = 6.4 kcal/mol of base pairs. Knowing ΔHc and the maximal slope of the degree of conversion, which was determined from the temperature dependence of the absorbance of polyU solutions at 260 nm, we were able to evaluate the parameter of cooperativity σ. From the relation σ = eΔFstack/RT the stacking free energy ΔFstack could be calculated. Dividing the apparent enthalpy of conversion by the calorimetrically measured enthalpy yields the cooperative length N0 of one helical segment at the midpoint of conversion. The results show that the type of the cation has no influence on the magnitude of ΔHc, whereas the cooperativity of polyU is influenced by the various cations.
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  • 85
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    Biopolymers 13 (1974), S. 861-862 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 86
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    Biopolymers 13 (1974), S. 903-908 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Clipped autocorrelation functions for the fluctuating intensity of light scattered from dilute solutions of poly-L-lysine in 0.2 M NaBr have been observed over a wide range of time scales down to 1.83 μsec, and over a wide range of pH. Two poly-L-lysine samples of molecular weight 35,000 and 200,000, respectively, were compared to determine the extent of draining of the so-called random-coil configuration. The observed correlation functions were in general very satisfactorily represented by simple translation diffusion of single molecules. At high pH ∼10-10.4, there was evidence of considerable aggregation, but no indication whatsoever of any unusually fast component, as reported recently by Jamieson et al. for poly-L-lysine HBr in the absence of salt.A 30% rise in the diffusion coefficient to a peak at pH 10 parallels the previously reported dip in the intrinsic viscosity, and is interpreted in terms of a more compact structure in that pH region between the coil and helix extremes.
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  • 87
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of deoxyribonucleoprotein (DNP) from calf thymus at different stages of deproteinization was studied.The dissociation of the first portion of histone produces no effect on the hydrodynamical and optical behavior of DNP particles. The conformational transition of a macromolecule was observed as soon as the ratio of protein to DNA ≤ 0.9.The effect of ionic strength on the conformation of DNP particles with high protein content was more strongly pronounced than that for DNA. On the contrary, DNP particles depleted of proteins (protein/DNA 〈 0.9) were found to be less sensitive than DNA to the variation of ionic strength. These data imply that the DNP molecules rich in proteins possess a superstructure that is destroyed as the protein/DNA ratio becomes 0.9.The data were analyzed in view of current theories on various model concepts. The most probable model to describe the DNP molecule was chosen by comparing the calculated and experimentally obtained parameters. We believe that DNP is best described as a “compressed coil,” possibly including superhelical regions.
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  • 88
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of some high-molecular-weight protenoid structures in radiofrequency cold plasma conditions are discussed. The fractionation results of the raw product and the spectrum of free and protenoid-bound amino acids are given. The uv analysis of these compounds is presented.A protein-forming mechanism that might have existed on the primitive earth is proposed.
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  • 89
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Double-stranded DNA can be readily adsorbed on mica or directly on carbon coated grids from the surface of solutions containing ethidium bromide, actinomine, or propidium diiodide. The DNA molecules are unfolded, well separated, and show a length distribution similar to molecules prepared by protein monolayer techniques.Since the intercalating dyes tested do not lead to an increased apparent diameter of the nucleic acid the method is useful for the study of nucleic acid-protein complexes. As a model, the binding of E. coli RNA polymerase to phage T7 and T3 DNA was examined under different conditions. The enzyme can easily be identified and its position along the DNA molecule can be mapped.
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  • 90
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of a series of oligopeptides (from the tripeptide to the octadecapeptide) with the repeating sequence L-norvalyl-glycyl-L-proline and a polytripeptide with this sequence are reported. The oligomers were synthesized step by step using the mixed anhydride method. All the products were chemically and optically pure. The polymer was prepared by the active ester method, using the p-nitrophenyl ester as the polymerizable tripeptide derivative. Good yield of relatively high average molecular-weight polymer was obtained. In the accompanying paper conformational investigations, both in solution and in the solid state, on the oligomers and the polymer are described.
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  • 91
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(Nδ-carbobenzoxy, Nδ-benzyl-L-ornithine) (PCBLO) was prepared by the standard NCA method. PCBLO was converted into poly(Nδ-benzyl-L-ornithine) (PBLO) through decarbobenzoxylation with hydrogen bromide. The monomer Nδ-benzyl-L-ornithine was synthesized by reacting L-ornithine with benzaldehyde, followed by hydrogenation. The conformation of the two polypeptides was studied by optical rotatory dispersion and circular dichroism. PCBLO forms a right-handed helix in helix-promoting solvents. In mixed solvents of chloroform and dichloroacetic acid (DCA) it undergoes a sharp helix-coil transition at 12% (v/v) DCA at 25°C, as compared with 36% for poly(Nδ-carbobenzoxy-L-ornithine) (PCLO). Like PCLO, the helix-coil transition is “inverse,” that is, high temperature favors the helical form. PBLO is soluble in water at pH below 7 and has a “coiled” conformation. In 88% (v/v) 1-propanol above pH (apparent) 9.6 it is completely helical. In 50% 1-propanol the transition pH (apparent) is about 7.4; this compares with a pHtr of about 10 for poly-L-ornithine in the same solvent.
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  • 92
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    Biopolymers 13 (1974), S. 1141-1160 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of ethidium bromide to DNA has been studied by various optical methods. From fluorescence polarization studies, and film, electric linear dichroism, and circular dichroism spectra, we propose assignments of the absorption bands of the dye, which are discussed in connection with wave-mechanical calculations recently reported.The optical activity induced in the dye absorption bands upon binding to DNA was attributed to various origins depending on the electronic transition considered. The visible absorption band displayed a circular dichroism due to the asymmetry of the binding site and independent of the amount of binding. The transition identified at 378 nm from the circular dichroism and electric dichroism observations was thought to be due to a magnetic-dipole transition. It remained constant with increasing amounts of dye bound. The main ultraviolet band showed circular dichroism characteristics corresponding to exciton interactions between dye molecules bound to neighboring sites.The electric dichroism observed for the strongly bound dye molecules indicated that the phenanthridinium ring of ethidium bromide was probably not perfectly parallel to the DNA base planes. When the amount of dye bound to DNA exceeded the maximum amount compatible with the exclusion of adjacent binding sites, the electric dichroism decreased owing to the appearance of externally bound dye molecules with no contribution to the dichroism.Sonicated DNA was used to study the lengthening of the DNA molecule upon complexation. Although the viscosity of the complexes increased with the amount of binding, the rotational diffusion coefficient measured by the electric birefringence relaxation was not detectably affected. The absence of variation in the electric birefringence with the binding indicated that the DNA base stacking remained unaltered.
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  • 93
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    Biopolymers 13 (1974), S. 1205-1212 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the polymerization of phenylalanine N-carboxyanhydride (NCA) using poly(N-methyl-L-or DL-alanine) diethylamide as initiator, the polymerization rate was L-NCA ≃ D-NCA 〉 DL-NCA. This is a new type of selective polymerization and indicates the incompleteness of earlier investigations to study the asymmetrically selective polymerization without D-NCA. Neither secondary structure nor optical activity of the polymeric initiator is a reason for the selectivity. Hence the cause for the selectivity was sought in the properties of the NCA's in solution. However, the selectivity was not observed in the polymerization initiated by poly(L-phenylalanine) dimethylamide. The importance of the initiator being a secondary amine type was suggested. The experimental results are discussed on the basis of these considerations.
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  • 94
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Classical potential energy calculations were performed for the dinucleoside phosphates UpA and GpC. Two widely accessible low-energy regions of conformation space were found for the ω′, ω pair. That of lowest energy contains conformations similar to helical RNA, with ω′ and ω in the vicinity of 300° and 280°, respectively. All five experimental observations of crystalline GpC, two of ApU, and the helical fragment of ApApA fall in this range. The second lowest region has ω′ and ω at about 20° and 80°, respectively, which is in the general region of one experimentally observed crystalline conformer of UpA, and the nonhelical region of ApApA.It is concluded that GpC and ApU, which were crystallized as either sodium or calcium salts, are shielded from each other in the crystal by the water of hydration and are therefore free to adopt their predicted in vacuo minimum energy helical conformations. By contrast, crystalline UpA had only 1/2 water per molecule, and was forced into higher energy conformations in order to maximize intermolecular hydrogen bonding.
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  • 95
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric dispersion measurements on poly-γ-benzyl-L-glutamate (PBLG) in dioxane and dioxane-dichloroacetic acid (DCA) mixtures in the frequency range 200 Hz-2 MHz were made in order to study the structure of molecular aggregates. The structure of aggregates is explained on the basis of the variation of dipole moment and relaxation time with degree of aggregation. PBLG was found to form linear head-to-tail-type aggregates in dioxane. These aggregates gradually reduce in size without loosing their α-helical structure during the process of disaggregation obtained by either adding DCA to the solution in dioxane or by heating. It was confirmed that the addition of 30 wt % DCA completely destroys the aggregation of PBLG in dioxane at 30°C. Thermal disaggregation, however, was not complete even at a temperature approaching the boiling point of the solvent.A reaction scheme for aggregation is proposed and equilibrium constants are calculated at various stages of aggregation. The enthalpy of aggregate formation is found to be -3 kcal/mol. Results of optical rotatory dispersion measurements of the helix-coil transition in this system are also presented.
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  • 96
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Zimm-Bragg parameters s and σ were determined for poly(γ-benzyl L-glutamate) (PBLG) in m-cresol and in dimethylformamide (DMF) from ORD data as a function of molecular weight. It was found that, within the temperature range between 10 and 55°C and on the average, s = 1.61 ± 0.1 and √σ = 0.04 ± 0.01 in m-cresol and s = 1.65 ± 0.05 and √σ = 0.045 ± 0.015 in DMF. The values of s in m-cresol decreased with increasing temperature, while the values of σ in the same solvent increased. This result for s suggests that PBLG in m-cresol will undergo a thermal helix-coil transition of normal type. The parameters in DMF showed no appreciable trend to vary with temperature. Aside from the difference between the two solvents, our results are consistent with existing data for various conformation-dependent properties such as light-scattering radius, intrinsic viscosity, and dipole moment, each indicating that the polypeptide chain has some flexibility in helicogenic solvents.
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  • 97
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    Biopolymers 13 (1974), S. 1391-1403 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of double-helical nucleic acids was calculated as a function of geometry, including terms involving n → π* transitions. The “nonbonding” n or σ orbitals were of the azine type, delocalized, but concentrated at the nitrogen atoms of the purines and pyrimidines. Dynamic coupling of the magnetic moments of the n → π* transitions with the electric moments of π → π* transitions generated important terms. Mixing of electric dipole character into n → π* transitions by the static electric field perturbation of the molecule is of lesser importance. The largest contributions of n → π* transitions to the circular dichroism of double-helical nucleic acids are comparable in magnitude to the sum of π → π* terms only for geometries where the circular dichroism is weak. Using both n → π* and π → π* contributions one is able to match experimental and calculated circular dichroism spectra for DNA's over a much wider range of conditions than was possible previously.
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  • 98
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    Biopolymers 13 (1974), S. 1435-1445 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser Raman spectra are reported for solid films cast from a series of solutions containing mixtures of right- and left-handed α-helices of poly-γ-benzyl-L- and D-glutamate. Procedures were established for producing spectra that were reproducible in position to ±0.3 cm-1 and in relative intensity to a few percent for features of interest. Spectra for the pure L and pure D polymers were identical, as expected. Several small but definite spectral changes appear in the mixtures, reaching a maximum for the racemic 50:50 mixture. The changes are a shift of -1.4 cm-1 in the amide I peak at 1650.5 cm-1; a shift of about -5 cm-1 in the partially resolved amide III peak at 1291 cm-1; a shift of +2.5 cm-1 in the benzyl peak at 3062.5 cm-1; changes in relative intensity of as much as 50% in several regions; and the marked enhancement of several peaks, particularly that at 254 cm-1. These changes are discussed in terms of side-chain interactions in the packing of right- and left-handed helices.
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  • 99
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    Biopolymers 13 (1974), S. 1535-1548 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Self-diffusion coefficient measurements have been applied to the study of Na+, Ca++, and Sr++ in the presence of a linear acidic polysaccharide extracted from cartilage, i.e., chondroitin sulfate. A series of experimental determinations was made with and without supporting electrolytes, and an analysis of experiments involving the separation of the electrostatic interaction terms by an extension of Manning's theory produced results showing the preponderant nature of these electrostatic terms. The specificity of each type of ion or the influence of the pH can be considered merely as higher order corrections with respect to the preceding interactions. Counterion concentration ranges and pH ranges were determined, where either the alkaline-earth counterions become free and hence move with their normal diffusion rate, or these cations are associated with the polyelectrolyte molecule, thus giving a diffusion coefficient similar to that of the macromolecule, or the apparent diffusion coefficients vary between these two extreme diffusion rates as a function of the association equilibria. This variation can be expressed as a function of the linear charge density parameter ξ related to the structure of the polyelectrolyte, the value of which was determined and found in good agreement with published values.
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  • 100
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    Biopolymers 13 (1974), S. 1635-1651 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism (CD) spectrum of polyproline II (PPII) has heretofore been moderately well calculated from exciton theory only at the expense of assuming unreasonable chain conformations and accepting a conservative spectrum in the 180-250-nm region (which is not observed). We have incorporated far uv transitions in the polarizability approximation and, together with the π2π* transition, have calculated the resulting correction to the exciton model. This has been accompanied by a modified assignment of the ππ* transition in PPII, and a simultaneous calculation of the absorption and CD spectra of the α-helix, β structure, PPI, and PPII. We obtain good agreement with the observed CD spectrum of PPII in the 180-250-nm region for acceptable chain conformations. In addition, we predict a negative CD into the far uv, in agreement with recent experimental observations. Our calculations also reproduce features of the far uv CD spectrum of the α-helix, and are in agreement with the CD spectra of the β chain and PPI. The calculated CD of the unordered polypeptide chain is not significantly influenced by far uv contributions, indicating that our previous calculation is valid for such a system. These results demonstrate the importance of incorporating far uv transitions in order to achieve an adequate theoretical explanation of the CD spectra of polypeptides.
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