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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 20 (1984), S. 38-51 
    ISSN: 1432-1432
    Schlagwort(e): Enzyme evolution ; Natural selection ; Multifunctional enzymes ; Gene duplication ; Enzyme specificity ; Metabolic evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is believed that all present-day organisms descended from a common cellular ancestor. Such a cell must have evolved from more primitive and simpler precursors, but neither their organization nor the route such evolution took are accessible to the molecular techniques available today. We propose a mechanism, based on functional properties of enzymes and the kinetics of growth, which allows us to reconstruct the general course of early enzyme evolution. A precursor cell containing very few multifunctional enzymes with low catalytic activities is shown to lead inevitably to descendants with a large number of differentiated monofunctional enzymes with high turnover numbers. Mutation and natural selection for faster growth are shown to be the only conditions necessary for such a change to have occurred.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 244 (1973), S. 77-79 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] A balance defect seen in a histidinaemic strain of mouse “segregates” abnormally, suggesting teratogenic effects of maternal metabolism. This effect may be analogous to certain human ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Table 1 Plasma amino acid values for different genotypes on various dietsDiet his/his Genotypes Histidine his/+ +/+ Genetic background Normal 2.83 ± 0.18 0.17 ± 0.02 0.12±0.007 50% Peru/50 % C57 Normal - 2% 6.08 ± 0.35 0.15 ± 0.06 0.13±0.09 ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-4927
    Schlagwort(e): histidine ammonia-lyase deficiency ; mouse ; isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The histidinemic (his/his) mutant mouse shows greatly reduced skin and liver histidine:ammonia-lyase (HAL; EC 4.3.1.3) activity compared with normal mice. Liver HAL activity in the mutant is heat and salt labile and is inhibited at high substrate concentrations. Two HAL components have been identified in the normal mouse liver, a minor component with properties similar to those of HAL of the mutant mouse and a major component which is heat and salt stable and insensitive to substrate inhibition. Immunotitration with anti-HAL antibody shows that the livers of mutant mice contain no detectable antigenically cross-reacting HAL protein. It is concluded, therefore, that the his allele is a null allele at a structural or regulatory locus for the major HAL enzyme and maps close to the HAL-regulatory locus Hsd and that the low residual HAL activity in the mutant is due to another enzyme.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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