Vitamin B_<12> and Spermatogenesis

Abstract

It has been reported that vitamin B_<12> (B_<12>)-deficiency could cause testicular injury. The biochemical mechanism for this event, however, has not yet been fully understood. In mammals, B_<12> is a cofactor for two enzymes, i.e. methionine synthase and methylmalonyl-CoA mutase. According to earlier studies, methionine synthase, rather than methylmalonyl-CoA mutase, may be responsible for the testicular injury when animals are in B_<12>-deficiency. Methionine synthase is one of key enzymes in methionine and folate metabolism, which is important for nucleic acid synthesis, protein synthesis, polyamine synthesis, and transmethylation. Here, we describe that properties of methionine synthase and discuss a possible biochemical mechanism for the testicular injury due to B_<12>-deficiency.