【摘要】 马红球菌（Rhodococcus equi）SHB-121胞内3-氰基吡啶水合酶经硫酸铵分级沉淀、DEAE-cellulose DE52和羟基磷灰石柱层析并经过Sephadex G-25处理,得到了聚丙烯酰胺凝胶电泳均一的3-氰基吡啶水合酶,纯化了31倍。该酶由一条肽链组成,其分子量为30kD,等电点为4.1。3-氰基吡啶水合酶能催化3-氰基吡啶水合生成尼克酰胺。酶反应最适pH为8.0,最适温度为30℃。Ag⁺、Hg²⁺、Cu²⁺及NH₄⁺对酶活力有强烈抑制作用。当以3-氰基吡啶为底物时,其K_m为0.1mol/L。NaCN为该酶反竞争性抑制剂,其K_i为5mmol/L。更多还原

【Abstract】 3-cyanopyridine hydratase from cell-free extract of methylacrylamide-induced Rhodococcus equi SHB-121 was purified by ammonium sulfate precipitation and column chromatography on DEAE-cellulose DE52, hydroxyapatite and Sephadex G-25. The enzyme was purified over 31-fold. The molecular weight of the enzyme estimated with SDS-PAGE was 30kD. The pI value was 4. 1. The optimum pH and temperature for the hydration were 8.0 and 30℃, respectively. The enzyme activity was inhibited by Ag+, Hg2+ and Cu2+ strongly. The transition temperature and pH were 7. 0℃ and 6.0, resulted from the differential spectra. The Km value for 3-cyanopyridine was 0. 1mol/L. Sodium cyanide was anticompetitive inhibitor, the K1 value was 5mmol/L.更多还原