Affiliations: Department of Biotechnology, Faculty of Engineering, Kansai University, Suita, Osaka‐Fu, 564‐8680, Japan | Institute for Chemical Research, Kyoto University, Uji, Kyoto‐Fu, 611‐0011, Japan
Abstract: Various vitamin B_6 enzymes play important roles in mammalian and microbial metabolism of selenium amino acids. Selenocysteine is synthesized from selenohomocysteine by catalysis of cystathionine \beta ‐synthase and cystathionine \gamma ‐lyase, which both require pyridoxal phosphate. Selenocysteine \beta ‐lyase, a new B_6‐enzyme, exclusively catalyzes \beta ‐elimination of selenocysteine, and occurs in mammalian systems and bacteria. Methionine \gamma ‐lyase, cysteine desulfurase, cysteine sulfinate desulfinase, and D‐selenocystine \alpha ,\beta ‐lyase, which are B_6‐enzymes, act on cysteine, cysteine sulfinate, D‐cystine, and their derivatives, and their selenium counterparts indiscriminately. Their reaction mechanisms are comparatively described.
Journal: Biofactors, vol. 10, no. 2-3, pp. 257-262, 1999
