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  • Chemistry  (27,175)
  • 2020-2023  (10)
  • 1970-1974  (27,165)
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  • 1
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26299 | 23782 | 2019-03-27 06:00:01 | 26299 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Keywords: Chemistry ; Fisheries ; Malaysia ; Pesticides ; Biological sampling ; Fish ; Fishery products ; Biochemical analysis ; Lethal limits
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: 71-74
    Format: 4
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  • 2
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26300 | 23782 | 2019-03-27 05:58:36 | 26300 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Keywords: Aquaculture ; Chemistry ; Fisheries ; Myanmar ; Pesticides ; Biological sampling ; Fish ; Fishery products ; Lethal limits
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: 75-83
    Format: 9
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  • 3
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26303 | 23782 | 2019-03-27 05:51:15 | 26303 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Keywords: Chemistry ; Fisheries ; Thailand ; Pesticides ; Biological sampling ; Fish ; Fishery products ; Dried products ; Lethal limits
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: 100-105
    Format: 6
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  • 4
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26826 | 23782 | 2019-11-21 00:56:12 | 26826 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Presented in the paper is the standard procedure in the determination of K value which is an index to measure the enzymatic freshness of fish and squid. Specifically, reagents, apparatus and the analytical procedures needed and the calculations are presented.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Chemical analysis ; Fishery products ; Fish inspection ; Fishery industry ; Food technology ; Standards ; Specifications
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: B-6.1-B-6.7
    Format: 7
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  • 5
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26825 | 23782 | 2019-11-21 00:52:35 | 26825 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Presented in the paper is the standard procedure in measuring K value in fish meat by means of the freshness testing paper technique.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Chemical analysis ; Fishery products ; Fish inspection ; Fishery industry ; Food technology ; Standards ; Specifications
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: B-7.1-B-7.2
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  • 6
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26802 | 23782 | 2019-11-12 05:28:20 | 26802 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Presented in the paper is the standard procedure in the measurement of pH in the fresh fish meat. Specifically, the procedures in sampling and sample preparation, apparatus and reagents required, and the analytical procedures are presented.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Chemical analysis ; Microbiological analysis ; Fishery products ; Processed fishery products ; Fish inspection ; Fishery industry ; Food additives ; Food technology ; Standards ; Specifications ; pH
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: A-3.1-A-3.2
    Format: 2
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  • 7
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26842 | 23782 | 2019-11-15 07:54:48 | 26842 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Starch is commonly used in the production of fish jelly products as an extender and as binding agent. The paper provides the methodology in the determination of starch in fish jelly products. Instructions for sample preparation and the reagents needed are presented. Detailed procedures in the determination of the starch in a sample are provided.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Chemical analysis ; Fishery products ; Fishery industry ; Food technology ; Standards ; Specifications ; Starch ; Additives ; Food additives
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: D-4.1-D-4.4
    Format: 4
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  • 8
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26852 | 23782 | 2019-11-15 07:36:44 | 26852 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Cholera is an acute specific infection caused by the organism, Vibrio cholera. Diagnosis may be confirmed by the presence of large numbers of the comma-shaped bacilli on direct microscopic examination of a fecal or vomitus smear, and by the isolation of the organism on culture. Fish and shellfish have been identified as vehicles of cholera. Large numbers of V. cholera must usually be ingested to cause cholera. Thus problems often occur when poor handling and inadequate refrigeration have allowed the organism to multiply. Presented in the paper is the methodology of determining the presence of Vibrio cholera in fish and fishery products.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Fishery products ; Fishery industry ; Food technology ; Standards ; Specifications ; Aerobic bacteria ; Microbiological analysis ; Microorganisms ; Pathogenic bacteria ; Pathogens ; Health and safety ; Public health ; Microbial contamination ; Vibrio cholerae
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: E-7.1-E-7.5
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  • 9
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26843 | 23782 | 2019-11-15 07:52:55 | 26843 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Sodium chloride is an important additive for the production of fish jelly products. It extracts the salt soluble protein to give the gel strength of the final product. The paper provides the methodology in the determination of the amount of sodium chloride in fish jelly products. Instructions for sample preparation and the reagents needed are presented. Detailed procedures in the determination of the salt in a sample are provided.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Chemical analysis ; Fishery products ; Fishery industry ; Food technology ; Standards ; Specifications ; Additives ; Food additives ; Salts ; Sodium chloride
    Repository Name: AquaDocs
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    Format: application/pdf
    Format: application/pdf
    Format: D-5.1-D-5.2
    Format: 2
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  • 10
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    Marine Fisheries Research Department, Southeast Asian Fisheries Development Center | Singapore
    In:  http://aquaticcommons.org/id/eprint/26851 | 23782 | 2019-11-14 01:29:31 | 26851 | Southeast Asian Fisheries Development Center, Marine Fisheries Research Department
    Publication Date: 2022-08-02
    Description: Food poisoning due to Vibrio parahaemolyticus is a food-borne infection resulting from the ingestion of a large number of this organism (about 106-109 viable cells). The major symptoms are diarrhea and abdominal pain with headache, fever, and vomiting also occurring. The organisms are excreted during the acute stage of the illness after which they decrease rapidly. The differentiation of V. parahaemolyticus from other pathogenic species of Vibrio is based mainly on salt tolerance, Voges-Proskauer reaction, fermentation of sucrose, and growth at 43°C. Presented in the paper is the methodology of determining the presence of Vibrio cholera in fish and fishery products.
    Keywords: Chemistry ; Fisheries ; Manuals ; Culture media ; Analysis ; Analytical techniques ; Methodology ; Fishery products ; Fishery industry ; Food technology ; Standards ; Specifications ; Aerobic bacteria ; Microbiological analysis ; Microorganisms ; Pathogenic bacteria ; Pathogens ; Health and safety ; Public health ; Microbial contamination ; Vibrio parahaemolyticus ; Vibrio cholerae
    Repository Name: AquaDocs
    Type: book_section
    Format: application/pdf
    Format: application/pdf
    Format: E-8.1-E-8.6
    Format: 6
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Abstract: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notes: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Keywords: Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Abstract: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notes: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
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  • 15
    ISSN: 1432-0827
    Keywords: Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Abstract: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notes: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
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  • 17
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    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Keywords: Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Abstract: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notes: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
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  • 18
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    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Keywords: Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des échantillons non lavés de phosphate de calcium amorphe (ACP) contiennent une fraction labile, non remplaçable, riche en phosphate acide avec un rapport Ca/P faible: cette fraction est perdue de façon irréversible au cours du lavage. De l'ACP frais, précipité entre pH 6.6–10.6, varie dans un rapport molaire Ca/P de 1.18 à 1.50 et dans un rapport HPO 4 2− /P total de 33.0% à 10.1%. A pH 7.40, de l'ACP frais a un rapport molaire Ca/P de 1.36±0.02 et contient 22.8 (±2.2)% HPO 4 2− . Les résultats obtenus avec du précipité non lavé ne peuvent s'expliquer par du Ca2+ emprisonné et de l'HPO 4 2− ou du Na+, Cl− et CO 3 2− exogènes. Les phosphates de calcium amorphes constituent une classe de sels ayant des caractères chimiques variables et des propriétés physiques identiques, comparables au verre. Le CaHPO4·xH2O non cristallin peut être un ACP, surtout au cours des phases précoces de formation. A des pH physiologiques, l'ACP se transforme en petits cristaux applatis contenant de fortes quantités de phosphate acide facilement remplaçable. Le fait de laver la couche de surface produit un changement chimique dans les nouveaux cristaux: des cristaux non lavés donnent des diagrammes de diffraction d'apatite peu cristallins, ainsi que des spectres infra-rouges peu nets, intermédiaires entre des apatites et du phosphate octocalcique. Des explications structurales sont proposées et les compositions minérales amorphe/cristalline de l'os et du cartilage sont recalculées.
    Abstract: Zusammenfassung Ungewaschene Proben von amorphem Calciumphosphat (ACP) enthalten eine unersetzliche labile Fraktion, welche reich an saurem Phosphat ist und ein niederes Ca/P-Verhältnis hat und welche während des Waschprozesses unwiderruflich verloren geht. Natives ACP, welches im pH-Bereich 6,6–10,6 ausgefällt wurde, variierte im molaren Ca/P-Verhältnis zwischen 1,18 und 1,50 und in HPO 4 2− /totales P zwischen 33,0 und 10,1%. Bei pH 7,40 hatte natives ACP ein molares Ca/P-Verhältnis von 1,36±0,02 und enthielt 22,8 (±2,2)% HPO 4 2− . Die Werte beim ungewaschenen Niederschlag rühren weder von aus dem Überstand aufgenommenem Ca2+ und HPO2−, noch von außen kommendem Na+, Cl− und CO 3 2− her. Die amorphen Calciumphosphate werden als eine Klasse von Salzen erkannt, welche veränderliche chemische, aber identische glasartige physicochemische Eigenschaften haben. Nicht kristallines CaHPO4·xH2O kann auch ein ACP sein, besonders in den frühen Bildungsstadien. Bei physiologischem pH verwandelt sich ACP in kleine plattenförmige Kristalle, welche große Mengen von leicht ersetzbarem saurem Phosphat enthalten. Das Waschen dieser Oberflächenschicht erzeugte chemische Veränderungen in den resultierenden Kristallen; ungewaschene Kristalle zeigten ein Diffraktionsmuster, das nur schwach demjenigen des kristallinen Aspatites glich, aber ein schlecht aufgelöstes Infrarotspektrum, welches zwischen Apatit und Octocalciumphosphat war. Es werden strukturelle Erklärungen für alle diese Phenomena diskutiert, und revidierte amorph/kristalline Mineralzusammensetzungen von Knochen und Knorpel wurden neu berechnet.
    Notes: Abstract Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca/P molar ratio from 1.18 to 1.50 and in HPO 4 2− /total P from 33.0% to 10.1%. At pH 7.40, native ACP had a Ca/P molar ratio of 1.36±0.02 and contained 22.8 (±2.2)% HPO 4 2− . Unwashed precipitate data could not be attributed to either trapped supernatant Ca2+ and HPO 4 2− or extraneous Na+, Cl−, and CO 3 2− . The amorphous calcium phosphates are recognized as a class of salts having variable chemical but identical glass-like, physicochemical properties. Non-crystalline CaHPO4·xH2O may also be an ACP, especially during early formative stages. At physiological pH, ACP transforms to small platy crystals containing large amounts of readily-replaceable acid phosphate. Washing this surface layer produced chemical alterations in the resultant crystals; unwashed crystals had poorly-crystalline apatitic diffraction patterns but exhibited poorly-resolved infrared spectra intermediate between apatite and octacalcium phosphate. Structural explanations for all these phenomena are discussed, and revised bone and cartilage amorphous/crystalline mineral compositions have been re-calculated.
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    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
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    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Keywords: Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Au cours de la phase inhabituelle de mue d'un isopode d'eau courante,Lirceuts brachyrus, la moitié postérieure de l'exosquelette est éliminée 24 heures avant la moitié antérieure. A ce stade, une reminéralisation se développe dans la partie postérieure alors que la partie antérieure est dans un stade de pré-mue. Le pourcentage de différence en calcium dans les deux moitiés à mi-mue et mue complète est respectivement de 22% (p〈0.01) et 33% (p〈0.01), indiquant une complexation du calcium pendant la mue. La rapidité de la reminéralisation est illustrée par le fait que le contenu minéral total double dans la partie postérieure entre la mi-mue et la mue totale et dans la partie antérieure entre la fin de la mue et un jour après. Le carbonate de calcium, sous forme de calcite, a pu être identifié par diffraction électronique de coupes fines des téguments.
    Abstract: Zusammenfassung Während der ungewöhnlichen Häutungssequenz des Frischwasser-IsopodenLirceus brachyurus (Harger) wird die hintere Hälfte des äußeren Skeletts 24 Std vor der vorderen Hälfte abgestoßen. In der halbgehäuteten Phase erfolgt Remineralisation im hinteren Teil, während der vordere Teil in einem Vorhäutungszustand ist. Der prozentuale Unterschied des Calciums in den zwei Hälften bei Halb- und Vollhäutungszustand ist 22% (p〈0,01) bzw. 33% (p〈0,01), was andeutet, daß Calcium während der Häutung abgesondert wird. Die Geschwindigkeit der Remineralisation erhellt aus der Tatsache, daß sich der Gesamtmineralgehalt im hinteren Teil zwischen Halt- und Vollhäutung, in der vorderen Hälfte jedoch zwischen Endhäutung und einem Tag nach der Häutung verdoppelt. Calciumcarbonat in kristalliner Calcitform wurde mittels Elektronendiffraktion von dünnen Hautschnitten nachgewiesen.
    Notes: Abstract During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p〈0.01) and33 (p〈0.01) respectively, an indication that calcium is sequestered during The rapidity of remineralization is illustrated by the fact that the total mineral content doubles in the posterior part between half and full molt and in the anterior half between the end of molt and one day after ecdysis. Calcium carbonate in the calcite cystalline form was demonstrated by electron diffraction of thin sections of the integument.
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    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Keywords: Fluorapatite ; Exchange ; Chemistry ; Crystallography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante: $$(Ca^2 )9.98(Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )0.02(PO_4^{3 - } )5.98(HCO_3^ - ,CO_3^{2 - } )0.02(F^ - )2$$ . L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante: $$(Ca)_5 (PO_4 )_3 OH solide + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F solide + (OH^ - )$$ , la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
    Abstract: Zusammenfassung Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht: $$(Ca^{2 + } )_{9,98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0,02} (PO_4^{3 - } )_{5,98} (HCO_3^ - ,CO_3^{2 - } )_{0,02} (F^ - )_2 $$ . Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion $$(Ca)_5 (PO_4 )_3 OH_{in fester Form} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{in fester Form} + (OH^ - )$$ wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
    Notes: Abstract A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to $$(Ca^{2 + } )_{9.98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0.02} (PO_4^{3 - } )_{5.98} (HCO_3^ - ,CO_3^{2 - } )_{0.02} (F^ - )_2 $$ . The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction $$(Ca)_5 (PO_4 )_3 OH_{solid} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{solid} + (OH^ - )$$ the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
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    Biopolymers 10 (1971), S. 1049-1057 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ultrastructural morphology and x-ray and electron diffraction of poly (Gly-Gly-Ala) have been studied. The polymer has two forms; the first, form I possesses a super-folded cross-β structure, long fibers of which show some twisting and intertwining. Form II precipitates in a less distinct fibrous form from aqueous solution. The x-ray diffraction and oriented electron diffraction data suggest that form II is a polyglycine II helix situated in a monoclinic cell with dimensions a = 8.86 Å, b = 22.0 Å, c = 9.42 Å, and β = 90°. Combined with the morphological evidence it appears likely that form II is also in an antiparallel superfolded array.
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    Biopolymers 10 (1971), S. 1099-1101 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: A statistical mechanical model was developed for use in connection with the problem of preferential binding of solvent components to proteins and of conformational transition in water-organic solvent systems. The model is a statistical one for the conformational transition of globular proteins induced by the adsorption of solutes in the solution, considered as a nearest-neighbor problem in statistical mechanics. Although a few illustrative examples are given, the actual interpretations of the experimental data using this theory are reserved for a later paper.
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    Biopolymers 10 (1971), S. 1103-1103 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Biopolymers 10 (1971), S. 1121-1138 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concept and representation of a logical tree as defined in computer science is applied to obtain a suitable representation of protein molecules in computer programs which handle or calculate atomic coordinates of protein molecules. On the basis of this analysis and of the analysis of the calculation and modification of the structure of a protein from bond lengths, bond angles, and dihedral angles, which is reproduced in an appendix, program modules which accomplish the various required computations are described. Three such modules are given in Iverson notation; in fact, it is hoped that this article will serve as a reasonably complete basis for the preparation of machine programs by moderately proficient programmers.
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    Biopolymers 10 (1971), S. 1207-1212 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism spectrum obtained from a dilute aqueous solution of poly (ala-gly-gly) resembles that described for charged polypeptides such as the salt form of poly glutamic acid. A similar spectrum is found for films cast from aqueous solution where x-ray studies reported elsewhere have indicated a poly-glycinc II conformation. Evidence is presented for a heat induced poly-glycine II to unordered state transition similar to that described for collagen. The interpretation of this, the first observation of the optical properties of a poly-amino acid in the poly glycine II conformation, is further rationalized on the basis of spectra obtained from a number of polypeptides whose conformation approaches that of a 31 helix.
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    Biopolymers 10 (1971), S. 1229-1242 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of cupric ion on the emission of tryptophan, tyrosine, and serum albumins is studied by emission spectroscopy and lifetime measurements. It is found that whenever cupric ion is bound to tryptophan or tyrosine, their emissions are quenched completely. The quenching may be due to an electron transfer mechanism. The fluorescence of complexes of cupric ions with serum albumins is partially quenched; this is because energy is transferred from tryptophan to the complexed cupric ions by a dipolar energy transfer mechanism. It is deduced from the present study that the tryptophan in the human serum albumin molecule is between 11 and 16 Å from the nearest eupric ion binding sites (assumed to be at the surface of the protein) and that one of the tryptophan in the bovine serum albumin molecule is very close to the cupric ion binding sites and the other is near the center of the bovine serum albumin molecule. It is also found that the deuterium solvent effect on serum albumin fluorescence is very small, and that the quenching of bovine serum albumin fluorescence at the N-F transition is the result of quenching of the fluorescence of both tryptophans. The phosphorescence lifetime apparatus, capable of measuring decay times of signals with intensities changing over a few orders of magnitude, and the ratio spectrofluorometer, both of which were constructed in this laboratory, are also described.
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    Biopolymers 10 (1971), S. 1253-1260 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The measurements were made for the volume and the sound velocity changes (ΔV and ΔU) on titrating the sodium salt of poly (S-carboxymethyl L-cysteine) with dilute HCl. For the reaction, —COO- + H+ → —COOH, ΔV per mole of H+ bound was + 12. 7 ml and +11. 4 ml in salt-free and 0. 2 M NaCl solutions, respectively. Corresponding ΔU was about -13 cm/sec in salt-free polymer solution where 11.5 mM carboxylate ion reacts with equimolar hydrogen ion. ΔV associated with the coil-to-β transition was found to be +2. 35 ml in H2O and +1. 90 ml in 0. 2 M NaCl per mole of amino acid residue, respectively. These values are larger than those obtained for the coil-to-helix transition of poly (L-glutamic acid). ΔU for the transition was about -30 cm/sec in salt-free solution of polymer concentration 0.0115 mole/liter. Possible sources of ΔV and ΔU for reaction; coil → β, are (1) the formation of void volume and (2) the changes in the extent of solvation in amide linkage and in side chain.
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    Biopolymers 10 (1971), S. 1317-1329 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of three aromatic molecules to apomyoglobin has been investigated. In each case equilibrium dialysis studies and tryptophan fluorescence quenching studies indicate that a one to one complex has been formed. The fluorescence quenching studies further suggest that the binding of the aromatic molecules is at the heme site with possible involvement of the arginine CD3. Xenon, which is known to quench the fluorescence of aromatic hydrocarbons, is found to be bound to apomyoglobin-aromatic molecule complexes and quenches the emission of the aromatic molecule in the complexes. Oxygen quenches pyrene fluorescence in water solution but does not quench the pyrene fluorescence from the apomyoglobin-pyrene complex. This is explained by a slower rate of diffusion of oxygen to pyrene in the apomyoglobin-pyrene complex.
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    Biopolymers 10 (1971), S. 1365-1369 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotor speed-dependent aggregation of T4 DNA in the analytical ultracentrifuge is studied in the presence of high pressure generated by compressed nitrogen gas in the cell. The extents of aggregation at various speeds are found to be practically the same in the presence and absence of pressure.
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    Biopolymers 10 (1971), S. 1331-1349 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time-dependent theory developed in Part I is specialized to treat tetrameric hemoglobin, and the results of the theory for dimeric-and tetrameric hemoglobin are compared with data on the kinetics of the reactions of hemoglobin with carbon monoxide and oxygen at various salt concentrations for the case of large concentration of ligand relative to that of hemoglobin. The fit of the theoretical results to the data suggests that hemoglobin at a 2 M salt concentration is predominantly dimeric and that the tetramer should be taken as the functional unit to explain the kinetics of the reactions of normal hemoglobin. A relationship is established between the time-dependent theory arid Adair's Intermediate Compound Hypothesis (I.C.H.) for hemoglobin, as brought to its present state by Gibson and Roughton. A generalization (G.I.C.H.) of the I.C.H. is presented and is shown to be equivalent to the time-dependent theory in the limit of infinite ligand concentration. The I.C.H. is shown to be an excellent approximation to the centralized theory (G.I.C.H.) in this limit.
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    Biopolymers 10 (1971), S. 1421-1425 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Biopolymers 10 (1971), S. 1427-1428 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Biopolymers 10 (1971), S. 1429-1454 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of oligodesoxyribonucleotides of various chain lengths to form complexes has been compared with that of oligoribonucleotides. Four series of oligonucleotidcs were prepared and investigated, i.e., dCn at acid pH versus rCn, dAn and dTn versus. rAn and rUn at neutral pH. The results indicate that in dilute solution, the formation of complexes is greatly facilitated in the case of desoxyoligomers and occurs for shorter oligomere than in the corresponding ribooligomers. The spectrophotometric titration of deoxyribooligo C indicates the appearance of two pK values in the 4-5 pH region characteristic of the double-stranded form, which occurs for much shorter dCn than rCn. The circular dichroism (CD.) spectra of deoxycytidylies in dilute solution starting from the trimer are conservative, characteristic of the double-stranded helical form of poly C at acid pH. In contrast, the CD spectra of a series of corresponding ribo Cn, under identical conditions is of nonconservative character similar to that of the single-stranded form of poly C at neutral pH, but differs in the band position. This spectrum is called intermediate. Only at higher concentrations of oligonucleotidcs (i.e., 10-3Minstead of 10-4M) does the circular dichroism spectrum of longer ribocytidylics assume conservative character. Thermal denaturation of deoxycytidylces at acid pH are strongly dependent on chain length and concentration, its one would expect for a cooperative helix-coil transition. The circular dichroism spectra measured at different temperatures shows one isosbestic point. In dilute solution, the standard-state enthalpy change found was 5-6 kcal/mole for higher oligomers (dC7). These properties are all in agreement with a structural transition from the d-Cn double-stranded form to a coil for n 〉 3. Studies of dAn and dTn in solutions of high ionic strength at low temperature indicate that complex formation occurs already at the level of trimer and for high oligomers. Under identical conditions a complex between rAn and rUn is detected only for oligomers longer than the hexamer. The nature of the “intermediate” form of oligoribo C at acid pH and low temperature was investigated by sedimentation and circular dichroism. A model of rCn is proposed of linear molecules which are partially double-stranded and partially single-stranded, which probably are slowly rearranged by “slippage” into a regular-double-stranded helical form.
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The number average molecular weight, Mn, of low molecular weight dextran was determined through endgroup analysis, and the intrinsic, viscosities of these materials in aqueous solution were determined at 25°C. The ultrasonic velocities in their aqueous solutions were also measured at 25 and 45°C. As concerns the molecular weight dependence of the intrinsic viscosity, partial specific compressibility of solute and the hound water around the solute, the following results were obtained. (1) log [η]-log Mn and [η]/Mn0.5 - Mn0.5 plots were in accord with the Mark-Houwink and Stockmayer-Fix-man equations respectively for Mn 〉 2, 000, but these plots deviated from the equations for Mn 〈 2, 000. (2)The partial specific compressibility, β1°, of dextran is expressed by following equation for Mn 〈 2,000: β1° = 10-12 × (13.6 log Mn - 51.7) (cm2/dyne). In contrast, it, becomes the constant value, -- 7.3 × 10-12 cm2/dyne, for Mn 〉 2,000. (3) The amount of bound water of dextran calculated from the sound velocity measurement lakes constant value of 0.17 ml g for Mn 〉 2, 000, but the amount of hydration increase with decreasing molecular weight for Mn 〈 2,000. From these results, a dextran molecule in aqueous solution is expected to change its conformation from random coiling to uncoiling stretched form at the molecular weight of around 2, 000 or about 12 glucose units.
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  • 37
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    Biopolymers 10 (1971), S. 1559-1581 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical rotation studies were performed on five compounds containing two peptide groups. Four of the molecules were confined to restricted regions of conformational space by the presence of closed rings. Solvent and temperature were varied, and theoretical calculations were done for each compound covering the appropriate conformational space. The interpretation which results is qualitatively successful over the conformational regions covered by the compounds. Quantitative correlation between theory and experiment will require compounds of high rigidity.
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    Biopolymers 10 (1971), S. 1617-1623 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy maps have been calculated for α-D-mannuronic acid (1-4) α-L-guluronic acid and for α-L-guluronic acid (1-4) β-D-mannuronic acid. These have been used, together with maps previously calculated for the homomonomeric dimers, to estimate the characteristic ratios and Kuhn lengths of the alternating copolymer and of a stochastic copolymer similar in composition to that extracted from L. digitata.The results show that the alternating copolymer is less extended than either homopolymer. Kuhn lengths calculated for the stochastic copolymer agree well with experimental results on high ionic strength solutions of alginate isolated from L digitata.
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  • 39
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    Biopolymers 10 (1971), S. 1635-1648 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly-S-carboxyethyl-L-cysteine, a higher side-chain homolog of poly-S-carboxymethyl-L-cysteine, has been prepared from poly-S-carbobenzoxyethyl-L-cysteine with hydrogen bromide in chloroform or acetic acid. The polymer is found to be in the β-conformation of an antiparallel arrangement of polypeptide chains in solid films, both in acid and salt forms, when examined by infrared spectra. Aqueous solutions of t he polymer have been investigated by measurements of rotatory dispersion and circular dichroism as well as by infrared spectra in D2O. These properties show sharp changes around pH 5.5, as the pH of solution is varied. At higher ionization the polymer is randomly coiled, but at lower ionization it is in the β-conformation. Dependence of the rotatory properties upon polymer concentration as well as on ionic strength has been observed even at the lowest degree of ionization attained, and this has been attributed to the formation of intermolecular β-conformation in solutions. The β-structure is characterized by a negative circular dichroic band at 223 mμ and a positive dichroic band at a wavelength lower than 200 mμ, and furt her by a negative bo value, -140°. The pH-induced coil-β transition of the polymer is compared with that of poly-S-carboxymethl-L-cysteine.
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    Biopolymers 10 (1971), S. 1681-1699 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The specific heat, of rat tail tendon at various water contents was measured as a function of temperature. The resulting graphs showed peaks arising from the melting, near 50°C, of helical material in the collagen, and from the melting of absorbed water in the range -40°C to 0°C. The heat of melting of helical material was 11.7 cal per gram of dry tendon. Determination of the heat and temperature of fusion of the absorbed water allowed resolution of the water into four states in the case of tendon before denaturation, and three states after denaturation. The four states are (1) water not freezable on cooling to - 70°C, (2) freezable water with-both heat and temperature of fusion different from the values for ordinary water, (3) freezable water with the heat of fusion of ordinary water, but a different temperature of fusion, and (4) water not distinguished from ordinary water. The fourth state was absent in denatured tendon. The results are discussed in terms of increasing size of clusters of absorbed water molecules.
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    Biopolymers 10 (1971) 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Biopolymers 10 (1971), S. 1743-1757 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absorption and rotatory properties of acridine orange-poly-S-carboxymethyl-L-cysteine system in water and in 0.2 M NaCl have been measured at different pH and polymer-to-dye mixing ratios. The absorption spectra indicate that the dyes are bound to the polymer in dimeric or highly aggregated forms. At neutral pH where the polymer is randomly coiled, no optical activity is induced on the absorption bands of bound acridine orange. At acid pH where the polymer has the β-conformation, a pair of positive and negative circular dichroic bands occur at each of the absorption bands, centered around 458 and 261 mμ. The signs of those bands are opposite to those found for α-helical poly-L-glutamic acid. A model for the binding of dye to the β-form polymer is presented, in which dimeric dyes are attached to ionized carboxyl groups and slack one another to form linear arrays on both sides of an extended polypeptide chain. The observed circular dichroism spectra can be explained by the Tinoco's exciton mechanism, based on this model. Low molecular weight poly-S-carboxymethyl-L-cysteine induces quite a different circular dichroism on bound acridine orange.
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    Biopolymers 10 (1971), S. 1853-1863 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dicrosim (CD) spectra of complexes of DNA with ethidiun bromnide, profiavine, 9-aminoacridine and 4-etliyl-9-amino-acridine have been determined between 220 and 450 nm, the range lieing extended to 600 nm for ethidiufm bromide. The variation of the magnitude of the visible and near - ultraviolet CD spectra of ethidium bromide - DNA complexes with the amount of ligand bound (r) suggests a common binding position with profiavine. On the other hand, 4-ethyl-9-aminoacndine complexed to DNA shows CD spectra not distinguishable from those of 9-aminnoacnidmc in both the visible and ultraviolet. The interpretation of these results with respect to the stereochemistry of the DNA-ligand complexes is discussed.
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    Biopolymers 10 (1971), S. 1901-1924 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The various treatments of sedimentation equilibrium are compared on a theoretical and an experimental basis. Particular attention is paid to the polyelectrolyte nature of the problem and the choice of a neutral component. The effective density gradients of several cesium salts for DNA are measured. Two previous theories for the effective density gradient are shown to be equivalent, and the experimental values are interpreted with respect to these theories. It is clear t hat sedimentation equilibrium in a density gradient may be used for the determination of unambiguous molecular weights.
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    Biopolymers 10 (1971), S. 1949-1972 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of friction-limited DNA unwinding is developed explicitly for moderate tind large perturbations. This extension of the earlier theory of the relaxation kinetics is necessary because of the complex nature of the rate limitation for small perturbations. The assumption of the theory that is violated under relaxation conditions is that base pairing reactions occurring at a constant local degree of twist of the strands are fast compared to the net unwinding of the molecule. However, these reactions that are slow for small perturbations have a large activation energy, and become faster than friction-limited un winding for large enough temperature jumps and sufficiently large DXA molecules. Thus only the rate for moderate and large perturbations is clearly limited by frictional resistance to turning the molecule in solution. The model used is a diffusional unwinding of the two strands, driven by the accompanying decrease in free energy. For large perturbations a numerical solution of the diffusion equation is required, since the diffusion coefficient is not constant. Two new parameters must be introduced into the equilibrium statistical theory to describe friction-limited unwinding kinetics. These are the force constant b, for winding up coil regions and the frictional coefficient per base pair βcfor rotating coil regions in solution. We find by fitting the theory to experiment that b = 1.8 × 10-13 ergs/ rad2- and βc = 3.5 × 10-21 erg see/base pair, both for DNA melted in alkali at 0.4.M Na + and ∼30 °C. The latter value is in agreement with predictions based on the viscosity of single stranded DNA in alkali. The quoted value of bcan be interpreted to mean that the number of conformational states of a nucleolide is reduced by an average factor of 1.55 when it is wound around another strand to the degree of twist in a double helix, but without forming a base pair.
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The properties of oligonucleotide helices of adeuylic- and uridylic acid oligomers have been investigated by measurements of hypo-and hyperchromieity. High ionic strengths favor the formation of triple helices. Thus, the double helix-coil transition can be studied (without interference by triple helices) only at low ionic-strength. A “phase diagram” is given representing the Tm-values of the various transitions at different ionic strengths for the system A(pA)17 + U(pU)17. Oligonucleolides of chain lengths 〈8 always form both double and triple helices at the nucleotide concentrations required for base pairing. For this reason the double helix-coil transition without coupling of the triple helix equilibrium can only be measured for chain lengths higher than 7. Melting curves corresponding to this transition have been determined for chain lengths 8, 9, 10, 11, 14 and 18 at different concentrations. An increase in nucleotide concentration leads to an increase in melting temperature. The shorter the chain length the lower the Tm-value and the broader the helix-coil transition. The experimental transition curves have been analysed according to a staggering zipper model with consideration of the stacking of the adeuylic acid single strands and the electrostatic repulsion of tlip phosphate charges on opposite strands. The temperature dependence of the nucleation parameter has been accounted for by a slacking factor x. The stacking factor expresses the magnitude of the stacking enthalpy. By curve fitting xwas computed to be 0.7, corresponding to a stacking enthalpy of about S kcal/mole. The model described allows the reproduction of the experimental transition curves with relatively high accuracy. In an appendix the thermodynamic parameters of the stacking equilibrium of poly A and of the helix-coil equilibria of poly A + poly U at neutral pH are calculated (ΔHA = -7.9 kcal/mole for the poly A stacking and ΔH12 = -10.9 kcal/mole for the formation of the double helix from the randomly coiled single strands). A formula for the configurational entropy of polymers derived by Flory on the basis of a liquid lattice model is adapted to calculate the stacking entropies of adenylic oligomers.
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    Biopolymers 10 (1971), S. 2049-2049 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Biopolymers 10 (1971), S. 2071-2077 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The data on the band widths and band shapes of several DNA's at various concentrations in sedimentation equilibrium in a CsCl density gradient have recently become available. In the present report, these literature data are treated in the following manner: (1) based on a theory of isotope-substitution, calculations are made of the molecular weights at infinite dilution, and (2) to explain the concentration dependence of band widths and band shapes, a theory of charge and hydration is put forth, and it is shown that by retaining the terms involving the charge of the macromolecules, it is possible to account for most of the concentration dependence.
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    Biopolymers 10 (1971), S. 2083-2094 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the unique and specific association of a given amino acid to its t-RNA is investigated by theoretical methods. Several possible schemes are proposed to explain specificity. The physical forces which act within these mechanisms are illustrated by the computer simulation of probable interactions between glycine and nucleotide bases and base pairs. It is demonstrated that glycine has direct and selective affinities for the nucleotide bases and that these interactions are principally determined by the polar groups. Energies have been calculated for the interaction of glycine with several base pairs. From these, the possibility that specificity arises through direct complexing of an amino acid with its anticodon is evaluated.
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    Biopolymers 10 (1971), S. 2147-2160 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equations are developed to describe the shift in the temperature of the helix-coil transition when small molecules bind to nucleic acids. Included are high polymers, oligonucleotides, and oligomer-polymer interactions. The equations prescribe simple ways of plotting experimental data to evaluate transition and binding parameters.
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