Dependence of Betaine Stimulation of Vitamin B12 Overproduction on Protein Synthesis
AUTOR(ES)
Fa, You-Hua
RESUMO
The betaine-stimulated differential synthesis of vitamin B12, i.e., the increase in B12 per increase in dry cell weight, by Pseudomonas denitrificans was inhibited by rifampin and chloramphenicol but not by benzylpenicillin and carbenicillin at concentrations of antibiotic that inhibit growth. The level of the first enzyme of corrin (and porphyrin) biosynthesis, δ-aminolevulinic acid synthetase, was decreased to a much greater degree by rifampin and chloramphenicol than by the penicillins. These data support the concept that betaine stimulation of B12 synthesis is a result of its stimulation of synthesis of δ-aminolevulinic acid synthetase, a labile and presumably rate-limiting enzyme of corrin formation requiring continuous induction. In further support of this hypothesis, it was found that chloramphenicol immediately interfered with both vitamin B12 and δ-aminolevulinic acid synthetase formation, no matter when it was added to the system.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=240058Documentos Relacionados
- Vitamin B12 absorption studies: effect of parenteral non-radioactive vitamin B12 on serum level of 57Co vitamin B12
- Betaine-Homocysteine Transmethylase in Pseudomonas denitrificans, a Vitamin B12 Overproducer
- Transport of vitamin B12 in Escherichia coli: energy dependence.
- ON THE MECHANISM OF CATALYSIS BY VITAMIN B12
- Repression of synthesis of the vitamin B12 receptor in Escherichia coli.
