Alternate Requirement for Vitamin B 12 or Methionine in Mutants of Pseudomonas denitrificans , a Vitamin B 12 -producing Bacterium
نویسندگان
چکیده
منابع مشابه
Vitamin B-12.
V itamin B-12 is a cofactor for 2 enzymes. In the cytoplasm, methionine synthase requires vitamin B-12 in the form of methylcobalamin and catalyzes the conversion of homocysteine to methi-onine by transfer of a methyl group from methyltet-rahydrofolate. This enzyme links the methylation pathway through synthesis of the methyl donor S-adenosyl methionine and the pathway in which purine and pyrim...
متن کاملIsolation of vitamin B 12 transport mutants of Escherichia coli.
Escherichia coli KBT001, a methionine-vitamin B(12) auxotroph, was found to require a minimum of 20 molecules of vitamin B(12) (CN-B(12)) per cell for aerobic growth in the absence of methionine. After mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and penicillin selection, two kinds of B(12) transport mutant were isolated from this strain. Mutants of class I, such as KBT069, were defect...
متن کاملThe Vitamin B 12 Coenzyme
INTRODUCTION In 19'58 Barker and his associates l 3 recognized a new coenzyme which controlled the conversion of glutamate into ,8-methylaspartate by Clostridium tetanomorph'im. The coenzyme was shown4 to be related to ",-vitamin B12, i.e. contair ing an adenine nucleotide grouping in place of the 5,6-dimethylbe:nziminalole nucleotide of vitamin B12, although similar coenzymes containing b{ nzi...
متن کاملRole of third serum vitamin B 12 binding protein in vitamin B 12 transport.
A third vitamin B(12) binding protein present in normal serum has been shown to participate in transport of labelled vitamin B(12) absorbed from the gut. All three vitamin B(12) binding proteins in serum were labelled at the same time after oral administration of vitamin B(12), implying that "free" vitamin B(12) reached the portal blood from the gut mucosa.
متن کاملLongitudinal concentrations of vitamin B(12) and vitamin B(12)-binding proteins during uncomplicated pregnancy.
BACKGROUND Because reference values for vitamin B(12) concentrations and vitamin B(12)-binding capacities for pregnant women have not been established, the reference values for nonpregnant women are often applied to assess vitamin B(12) status. The aim of the present study was to describe ranges of biochemical indices of vitamin B(12) status, including red blood cell (RBC) vitamin B(12), satura...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of Bacteriology
سال: 1969
ISSN: 0021-9193,1098-5530
DOI: 10.1128/jb.99.1.347-349.1969