A Differential Microbiological Assay for Vitamin B 12 and Pseudovitamin B 12

Diagnosing vitamin B-12 deficiency on the basis of serum B-12 assay.

service Email alerting box at the top right corner of the article Receive free email alerts when new articles cite this article-sign up in the

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...

Rapid microbiological assay of serum vitamin B 12 by electronic counter.

A new method of measuring the growth of Lactobacillus leichmannii is reported. Its adoption for the estimation of serum vitamin B(12) levels shortens the incubation period required to five hours at 45 degrees C. The method is compared statistically with a standard method of estimation, requiring incubation at 37 degrees C., by duplicate determinations on 106 hospital patients. The significance ...

The 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...

Coated charcoal assay of erythrocyte vitamin B 12 levels.