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  • Artikel  (6)
  • Burkard sporetrap  (2)
  • Chlamydomonas (l-amino-acid oxidase)  (2)
  • Holocene  (2)
  • Springer  (6)
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  • Artikel  (6)
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  • Springer  (6)
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  • 1
    ISSN: 1432-2048
    Schlagwort(e): l-amino-acid oxidase (molecular properties) ; Chlamydomonas (l-amino-acid oxidase) ; Flavoprotein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Anl-amino-acid oxidase (EC 1.4.3.1) that catalyzes the oxidative deamination of twelvel-amino acids has been purified 21-fold and with 14% yield to electrophoretic homogeneity fromChlamydomonas reinhardtii cells by ammonium-sulfate fractionation, gel filtration through Sephacryl and Superose, anion-exchange chromatography and preparative electrophoresis in polyacrylamide gels. The native enzyme is a protein of 470 kDa and consists of eight identical or similarsized subunits of 60 kDa each. Optimum pH and temperature were 8.2 and 55° C, respectively, with a Q10 (45–55° C) of 1.7 and an activation energy of 45 kJ · mol−1. Its absorption spectrum showed, in the visible region, maxima at 360 and 444 nm, characteristic of a flavoprotein with a calculated flavin content of 7.7 mol FAD per mol of native enzyme. ApparentK m values of the twelvel-amino acids which can act as substrates ofl-amino-acid oxidase ranged between 31 μM for phenylalanine and 176 μM for methionine. The effect of several specific group reagents, chelating agents and bivalent cations on enzyme activity has also been studied.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-2048
    Schlagwort(e): l-amino-acid oxidase (molecular properties) ; Chlamydomonas (l-amino-acid oxidase) ; Flavoprotein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An l-amino-acid oxidase (EC 1.4.3.1) that catalyzes the oxidative deamination of twelve l-amino acids has been purified 21-fold and with 14% yield to electrophoretic homogeneity from Chlamydomonas reinhardtii cells by ammonium-sulfate fractionation, gel filtration through Sephacryl and Superose, anion-exchange chromatography and preparative electrophoresis in polyacrylamide gels. The native enzyme is a protein of 470 kDa and consists of eight identical or similarsized subunits of 60 kDa each. Optimum pH and temperature were 8.2 and 55° C, respectively, with a Q10 (45–55° C) of 1.7 and an activation energy of 45 kJ · mol−1. Its absorption spectrum showed, in the visible region, maxima at 360 and 444 nm, characteristic of a flavoprotein with a calculated flavin content of 7.7 mol FAD per mol of native enzyme. Apparent K m values of the twelve l-amino acids which can act as substrates of l-amino-acid oxidase ranged between 31 μM for phenylalanine and 176 μM for methionine. The effect of several specific group reagents, chelating agents and bivalent cations on enzyme activity has also been studied.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1573-3025
    Schlagwort(e): Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of pollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1573-3025
    Schlagwort(e): Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of bollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1617-6278
    Schlagwort(e): Pollen analysis ; Late-glacial ; Holocene ; Iberian peninsula
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Klassische Archäologie , Biologie
    Notizen: Abstract This paper presents the results of pollen analyses from organic sediments of seven cores (299 spectra) in a mountainous area of the north-west Iberian peninsula. The pollen diagrams, supported by seven14C dates, are used to construct a regional pollen sequence covering the main stages of vegetation dynamics, from the last phases of the Late-glacial until the present. During the Late-glacial Interstadial an important development of cryophilous forests (Betula andPinus) was recorded, although various mesophilous and thermophilous tree elements were also present. The Younger Dryas, palynologically clearly defined, is characterized by an important reduction in tree pollen percentages and the expansion of steppe formations (Poaceae andArtemisia). At the beginning of the Holocene, there was an expansion ofQuercus and a spread of other trees, which combined to give a vegetation cover of varied composition but dominated by mixed deciduous forests. Such forest formations prevailed in these mountains until 3000 years ago, when successive deforestation phases are recorded at various times as a result of increased farming activity. The results are compared with data from other mountainous areas in the northern Iberian peninsula and southern France.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1573-5052
    Schlagwort(e): Holocene ; Lateglacial ; North Iberian Peninsula ; Pollen analysis ; Vegetation development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The dynamics of vegetation in the North Iberian Peninsula have been historically established from peaty and lacustrine records obtained in strongly continental mountainous areas. Pollen records located in areas with a more oceanic climate, have allowed a more precise evaluation of the changes and differences in the vegetation development of the various biogeographical areas in the North Iberian Peninsula, during the Late-glacial and Holocene. It was found that: (1) The vegetation of the Cantabrian–Atlantic province in northern Iberian Peninsula responded to climatic changes during the last 16000 years. (2) Tree vegetation declined during the Oldest Dryas, with steppe vegetation in the interior and cryophilous vegetation along the coast. (3) During the time of the Lateglacial Interestadial, lowlands, arboreal vegetation was dominant in the landscape (Pinus, Betula, Quercus, Corylus). (4) During the Younger Dryas the differences between coast and interior are less obvious. (5) During the Holocene oceanic decidious forests of Quercus robur, Corylus avellana, Tilia sp. and Fagus sylvatica were present along the coast. At low altitudes, in the interior, forests of Quercus robur / pyrenaica, enclaves of pine woods and Mediterranean types of forest (Quercus ilex, Olea europea) were present. At higher altitudes Pinus (P. sylvestris and P. uncinata) or mixed forests of Pinus and Betula were dominant.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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