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  • 1
    ISSN: 1432-072X
    Keywords: Blue-green algae ; Cyanobacteria ; Glutamine synthetase ; Light-modulation ; Anabaena cylindrica ; NH 4 + -deactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extractable glutamine synthetase activity of the cyanobacterium Anabaena cylindrica was reduced by approximately 50% when N2-fixing cultures were treated with 10 mM NH 4 + or were placed in darkness. The deactivated enzyme could be rapidly reactivated (within 5 min) by adding 40 mM 2-mercaptoethanol to the biosynthetic reaction mixture. The enzyme could also be reactivated in vivo by replacing the culture in light or by removing NH 4 + . When the enzyme was deactivated by simultaneously adding NH 4 + and placing the culture in darkness, reactivation occurred on reillumination and removal of NH 4 + . The removal of NH 4 + in darkness did not result in reactivation. On in vitro reactivation of glutamine synthetase from dark or NH 4 + -treated cultures the maximum glutamine synthetase activity observed frequently exceeded that of glutamine synthetase extracted from untreated cultures. Anacystis nidulans showed a similar type of reversible dark deactivation to A. cylindrica but Plectonema boryanum and a Nostoc did not. With A. cylindrica, a direct positive correlation between the size of the intracellular pool of glutamate and biosynthetic glutamine synthetase activity occurred during light/dark shifts, and on treatment with NH 4 + . The changes in activity of glutamine synthetase in A. cylindrica in response to light resemble in some respects the light modulation of enzymes of the oxidative and reductive pentose phosphate pathways noted in cyanobacteria by others.
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  • 2
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Enterolobium contortisiliquum trypsin inhibitor (EcTI) belongs to the Kunitz family of plant inhibitors, which are widely distributed in nature, especially in plant seeds. EcTI is composed of two polypeptide chains with a total of 174 residues, homologous to other inhibitors from the same family. EcTI crystals, which were obtained with the acupuncture-gel technique, diffract to 2.0 Å resolution and belong to space group P21, with unit-cell parameters a = 37.12, b = 38.42, c = 54.08 Å, β = 98.08°. Molecular-replacement techniques using Erythrina caffra trypsin inhibitor (PDB code 1tie) as the search model indicate one monomer in the asymmetric unit. The secondary-structure content of EcTI was determined by circular dichroism spectroscopy, yielding values compatible with the expected topology.
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of medicinal chemistry 18 (1975), S. 1159-1161 
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 21 (1965), S. 72-73 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Anhand zweier Versuchsanordnungen wird gezeigt, dass Meskalin Histaminwirkungen verstärken kann. Ausserdem vermag es die Histamin zerstörende Wirkung der Diaminooxydase zu hemmen (in 10−5-molarer Konzentration). Es wird die Möglichkeit diskutiert, dass diese Eigenschaften mit der 4-Methoxyphenyl-äthylamin-Struktur des Meskalins in Zusammenhang stehen könnten.
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  • 5
    ISSN: 1573-4943
    Keywords: Leguminosae ; protein sequencing ; Torresea acreana, serine proteinase inhibitor, Bowman-Birk inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract TaTI (Torresea acreana trypsin inhibitor), a new member of the Bowman-Birk trypsin inhibitor family, was purified from seeds ofTorresea acreana, one of the two known species ofTorresea, a Brazilian native Leguminosae of the Papilionoideae subfamily. Purification was performed by acetone fractionation, anion-exchange chromatography, and gel filtration. The TaTI appears asM r 7000 in SDS-PAGE under reducing conditions. There are 63 amino acid residues present in the TaTI sequence, which was confirmed by mass spectrometry (8388 daltons). The putative reactive sites residues were Lys-15 and Arg-42 at the first and second site, respectively. The antibodies raised against TcTI2,Torresea cearensis trypsin inhibitor 2, showed a cross-reaction with TaTI, but not with other Bowman-Birk inhibitors purified from Leguminosae. The inhibition constants of TaTI and TcTI2 were comparable when measured against trypsin, chymotrypsin, and factor XIIa, but not on plasmin. The latter was tenfold more effectively inhibited by TcTI2 then by TaTI. Neither TaTI nor TcTI2 affects thrombin, plasma kallikrein, or factor Xa.
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  • 6
    ISSN: 0032-8332
    Keywords: Cebus apella ; Heterozygosity ; Glyoxalase ; New World monkeys ; Genetic variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An analysis of seven loci inCebus apella paraguayanus showed that Glyoxalase I was polymorphic due the appearance of two alleles (GLO*2 andGLO*3) with frequencies of 0.955 and 0.045, respectively. Of the two alleles,GLO*2 was electrophoretically similar to the most common allele found in the human andAotus. These results confirmed our previous findings in the same population sample showing that this subspecies has a very low genetic variation among New World primates.
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  • 7
    ISSN: 0032-8332
    Keywords: Saguinus fuscicollis ; Saguinus midas ; Heterozygosity ; New World Monkeys ; Genetic variability ; Genetic distances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study of 20 blood genetic systems was performed on three populations of genusSaguinus: S. fuscicollis weddelli, S. midas niger, andS. midas midas. Some markers are useful for the characterization of the two species.ADA 5, ADA6, CA23, CA24, andES2 2 occur only inS. fuscicollis whileADA 4is fixed inS. midas. S. midas midas showed heterozygosity value comparable to those previously obtained for the genusAlouatta. Estimates of genetic distance betweenS. fuscicollis andS. midas species of about 14% are in accordance with those referred to in the literature for interspecific differences. Genetic distances between subspecies ofSaguinus midas were nearly 3%, which is within the range for subspecies.
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  • 8
    ISSN: 0032-8332
    Keywords: Callithrix ; Heterozygosity ; Biochemical markers ; Taxonomy ; Polymorphism ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The electrophoretic patterns of 15 protein systems codified for 20 genetic loci were investigated using horizontal electrophoresis. A total of 150 blood samples, from five species of the genusCallithrix were analyzed. Polymorphic variation was observed in 10 out 20 loci analyzed. The genotypic distributions are in Hardy-Weinberg equilibrium. The average heterozygosity (H) varied from 1% to 5%, similar to those observed for other Neotropical primates. The genetic distance coefficients revealed a phylogenetic separation of these species into two groups: (1) “argentata” (C. humeralifer andC. emiliae); (2) “jacchus” (C. jacchus, C. penicillata, andC. geoffroyi). This arrangement is according to the taxonomic arrangement proposed byHershkovitz (1977),de Vivo (1988), andMittermeier et al. (1988). The results in each group are compatible with the subspecies values recorded for the Platyrrhini. These values showed that:C. humeralifer andC. emiliae are subspecies ofC. argentata;C. jacchus, C. penicillata, andC. geoffroyi are subspecies ofC. jacchus. These results also suggest thatC. j. geoffroyi is the “jacchus” group taxon, most similar genetically to the “argentata” group.
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  • 9
    ISSN: 1617-4623
    Keywords: Hydrogenase activity ; Transcriptional regulation ; Bradyrhizobium japonicum ; Alcaligenes eutrophus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Bradyrhizobium japonicum, Tn5 insertions in a particular chromosomal DNA fragment result in a Hup− phenotype in free-living conditions without affecting hydrogenase (Hup) activity in the symbiotic state. By determination of the nucleotide sequence of this region, we were able to identify the nature of the inactivated genes. The fragment is located 9 kb downstream of the hydrogenase structural genes and contains one incomplete and three complete open reading frames. They are designated hypD′, hypE, hoxX and hoxA respectively, since the deduced amino acid sequences display very strong homology with genes involved in the regulation of hydrogenase activity in Escherichia coli, Rhodobacter capsulatus, Azotobacter vinelandii (hypD′ and hypE) and Alcaligenes eutrophus (hoxX and hoxA). This is the first report on transcriptional activators of the hup genes in B. japonicum. Implications of these findings with respect to regulation of hydrogenase synthesis by hydrogen, oxygen and nickel in free-living B. japonicum are discussed.
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  • 10
    ISSN: 1617-4623
    Keywords: Bertholletia excelsa H.B.K. ; Brazil nut ; cDNA cloning ; Methionine-rich storage protein ; Precursorproduct relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seed storage proteins were extracted from Brazil nut (Bertholletia excelsa H.B.K.) seed embryos at various maturation stages. Salt-soluble and water-soluble proteins (globulins and albumins) were separated by gel chromatography and exhaustive dialysis against water. Both fractions were analysed by one- and two-dimensional polyacrylamide gel electrophoresis. Amino acid analysis revealed that both fractions are unusually high in methionine. The albumins consist of a family of low molecular weight polypeptides that are heterogeneous with respect to pI and are identical to the high methionine 2 S proteins described by Youle and Huang (1981). The biosynthesis of this class of proteins in maturing embryos was followed by in vivo labelling combined with immunological studies. Western blotting with monospecific antibodies against purified 2 S albumins and sequencing of a nearly complete cDNA clone revealed that they are synthesized via a precursor polypeptide.
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