| 生化机理 |
Vitamin B12 (cobalamin) refers to a group of chemically-related cobalt containing molecules involved in cell processes such as DNA synthesis, fatty acid synthesis, energy production and regulation. The physiologically active forms of vitamin B12 include methylcobalamin and adenosylcobalamin, whereas hydroxocobalamin (vitamin B12a, OHCbl) and cyanocobalamin (CNCbl) are storage and delivery forms. Bacteria-derived hydroxocobalamin (OHCbl) and CNCbl are converted in humans to useful coenzyme forms to support metabolic processes such as mitochondrial methylmalonylcoenzyme A mutase conversion of methylmalonic acid (MMA) to succinate to link lipid and carbohydrate metabolism, and activation of methionine synthase, the rate limiting step in the synthesis of methionine. |
