細菌のセレノシステイン代謝に関与する酵素

抄録

We have found the presence of a new enzyme in various mammalian tissues, that cleaves specifically L-selenocysteine into L-alanine and H₂Se and named it selenocystein β-lyase (Esaki, N. et al. (1982) J. Biol. Chem. 257 :4386). In this paper, the distribution of the enzyme in microorganisms and some properties of the bacterial enzyme are described. The enzyme occurs widely in aerobic bacteria such as A. viscolactis. However, no significant activity is detected in yeasts and fungi. Like the pig liver enzyme, the enzyme from A. viscolactis acts specifically on L-selenocysteine (Km: 0.8mM), requires pyridoxal 5'-phosphate as a cofactor (Km: 5μM) and is competitively inhibited by L-cysteine (Ki: 0.2mM).