SCLY, also known as selenocysteine lyase, belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family. It is a novel enzyme that exclusively decomposes L-selenocysteine into L-alanine and H2Se in various mammalian tissues. SCLY contains pyridoxal 5'-phosphate and weighs approximately 85,000. SCLY participates in selenoamino acid metabolism. It employs one cofactor, pyridoxal phosphate. Its maximum reactivity is at about pH 9.0. It was shown that 1 mol of selenocysteine is converted to equimolar amounts of alanine and H2Se. The following amino acids are insert: L-cysteine, L-serine, L-cysteine sulfinate, selenocysteamine, Se-ethyl-DL-selenocysteine, and L-selenohomocysteine. L-Cysteine (Ki, 1.0 mM) competes with L-selenocysteine (Km, 0.83mM) to inhibit the enzyme reaction.
