The phosphatase of a psychrophile (Shewanella sp.) was purified by ammonium sulfate fractionation, followed by sequential column chromatographies. The purified enzyme was electrophoretically homogeneous on native- and SDS-PAGE. Its molecular weight was 41,826 by its amino acid composition. The enzyme had its optimal pH for the activity at 9.8, and a broad substrate specificity to dephosphorylate ATP, pyrophosphate, glycerophosphate, and so on. Its activity was increased by metal ions including Mg2+, Mn2+, and Co2+. The maximal activity was observed at 40°C, and the enzyme at 0°C showed 39% of activity at 40°C. The enzyme, however, tended to lose its activity at 20°C and pH 9.8. These results indicated that purified enzyme was an alkaline phosphatase with characteristics; high catalytic efficiency at low temperature and gradual inactivation at an intermediate temperature.
一种嗜冷菌(希瓦氏菌属)的
磷酸酶通过
硫酸铵分级分离,随后进行连续的柱层析纯化。纯化后的酶在天然聚
丙烯酰胺凝胶电泳和
SDS-聚
丙烯酰胺凝胶电泳中呈现电泳均一性。根据其
氨基酸组成,其分子量为41,826。该酶的最适活性pH值为9.8,对去
磷酸化的底物如
ATP、
焦磷酸盐、
甘油磷酸盐等具有广泛的底物特异性。
金属离子如Mg²⁺、Mn²⁺和Co²⁺可以增强其活性。最大活性在40°C时被观察到,而在0°C时该酶显示出40°C活性的39%。然而,该酶在20°C和pH 9.8时倾向于失去活性。这些结果表明,纯化后的酶是一种碱性
磷酸酶,具有在低温下高催化效率和中温下逐渐失活的特性。