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Humans, as well as other mammals, must convert ingested vitamin B12 to active coenzyme forms for biologic activity. We found that human fibroblasts in tissue culture are capable of carrying out this conversion and we report a method to measure the accumulation of newly synthesized coenzymes by the cultured cells. Fibroblasts are grown in culture medium which contains the precursor vitamin, 57Co-hydroxocobalamin. After 4 days the cells are harvested. Cobalamins are extracted from the cells and then separated by thin layer chromatography. In addition to the hydroxocobalamin, two peaks of radioactivity are found which correspond to the coenzyme forms of B12, deoxyadenosylcobalamin and methylcobalamin. The ability to study coenzyme synthesis and accumulation in human cells will enable investigation of normal B12 metabolism and of human disease states where abnormal metabolism is suspected.
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Accepted: May 12, 1971
Received: February 15, 1971
☆Supported by research grants from the John A. Hartford Foundation and the National Institutes of Health (AM 12579).
© 1971 Published by Elsevier Inc.