Ribonucleotide reductase activity in vitamin B12-deficient Euglena gracilis
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منابع مشابه
Ribonucleotide reductase activity in vitamin B12-deficient Euglena gracilis.
The ribonucleotide reductase activities in vitamin B12-sufficient and -deficient cells of Euglena gracilis were measured. We found that the cells progress into vitamin B12 deficiency the enzyme activity increases, reaching a maximum value of 20-fold in advanced deficiency. No signigicant differences in the activities were found to result as a consequence of different growth conditions. We propo...
متن کاملEuglena gracilis ribonucleotide reductase: the eukaryote class II enzyme and the possible antiquity of eukaryote B12 dependence.
Ribonucleotide reductases provide the building blocks for DNA synthesis. Three classes of enzymes are known, differing widely in amino acid sequence but with similar structural motives and allosteric regulation. Class I occurs in eukaryotes and aerobic prokaryotes, class II occurs in aerobic and anaerobic prokaryotes, and class III occurs in anaerobic prokaryotes. The eukaryote Euglena gracilis...
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Ribonucleoside triphosphate reductase (RTPR) from Lactobacillus leichmannii catalyzes the conversion of ribonucleotides to 2'-deoxyribonucleotides and requires adenosylcobalamin (AdoCbl) as a cofactor. Recent cloning, sequencing, and expression of this protein [Booker, S., & Stubbe, J. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 8352-8356] have now allowed its characterization by site-directed mut...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1980
ISSN: 0306-3283
DOI: 10.1042/bj1880573