ON THE METABOLISM OF COENZYME B12:III. CONVERSION PROCESS AND RATE FROM CYANOCOBALAMIN AND HYDROXOCOBALAMIN INTO COENZYME B12 IN THE BODY

概要

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1. The metabolism of vitamin B12 in the body of rats and human subjects was examined.2. Fractionation of three cobamides, CN-B12, OH-B12 and DBCC, and their identification were carried out.3. The conversion from cyanocobalamin or hydroxocobalamin to coenzyme B12 was found to take place in the liver and kidneys of rats and humans. Considerable quantities were converted in a short time. In fact, more than half of the administered derivatives were converted into the coenzyme in 48 hours.4. The conversion from hydroxocobalamin to the coenzyme was faster than that from cyanocobalamin, which means that hydroxocobalamin is favorable for utilization of the vitamin.5. The conversion rate in question was higher for the vitamin deficient rats than that for normal rats, showing that the requirement for the coenzyme is increased in the case of the deficient rats.6. The conversion rate in the liver was lower in the carbon tetrachloride-injured rats and in the damaged human liver than that of normal ones. In these cases the conversion rate from hydroxocobalamin to the coenzyme was not changed appreciably as compared with the normal, showing that hydroxocobalamin is more available in the case of liver damage.7. The intrinsic factor gives rise to an increase of the hepatic uptake and the quantity converted.
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