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 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 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 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 کاملEffects of Weaning, Fasting and B-vitamin Injections on Plasma B-vitamin Concentrations in Beef Calves
Twelve 364 Ib beef calves were weaned, limit-fed and fasted for three days during the 20-day period after weaning, and then inoculated intranasally with live attentuated infectious bovine rhinotracheitis on day 20. Six of these calves were injected intramuscularly with water soluble vitamins every 2 days from day 9 to day 34. Plasma ascorbic acid and pantothenic acid were depressed by weaning a...
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ژورنال
عنوان ژورنال: BMJ
سال: 1985
ISSN: 0959-8138,1468-5833
DOI: 10.1136/bmj.291.6487.56-a