Soluble δ-Aminolevulinic Acid Synthetase of Rat Liver

摘要: Abstract The present study describes some characteristics of soluble hepatic δ-aminolevulinic acid synthetase, including end product inhibition by hemin. enzyme is shown to contain a —SH group at its active center which associated with the initial binding cofactor pyridoxal-5'-PO4 enzyme. In addition, may influence activation synthetase divalent cations. A mechanism suggested for catalytic formation from glycine and succinyl-CoA. From data derived isotopic studies [1 -14C]glycine, utilizing specific inhibitors, following sequence reactions resulting in proposed. thiohemiacetal between pyridoxal-5'-PO4; subsequent Schiff base followed condensation succinyl-CoA; enzymatic reaction terminated decarboxylation glycyl carboxyl association release End mammalian was confirmed using hemin, demonstrated have Ki 2 x 10-5 m. various metalloporphyrins, porphyrins, bilirubin also inhibit activity. relative potencies inhibitors appear be dependent on net charge tetrapyrrole.