Khandelwal R L
Can J Biochem. 1979 Dec;57(12):1337-43. doi: 10.1139/o79-178.
A simplified procedure for the purification of low molecular weight phosphoprotein phosphatase acting on muscle phosphorylase a has been described from rabbit heart. The enzyme was purified to homogeneity by acid precipitation, ethanol treatment, and chromatography on Sephadex G-75 and Sepharose-histone. The purified enzyme showed a single band when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; the molecular weight calculated by this method was 34 000. The S20, W value and Stokes radius for the enzyme was 3.35 and 24.0 A(1 A = 0.1 nm), respectively. Using these two values, a molecular weight of 35 000 was calculated. Purified enzyme showed a wide substrate specificity and catalyzed the dephosphorylation of phosphorylase a, glycogen synthase D, phosphorylated histone, and phosphorylated casein. Kinetic studies revealed the lowest Km with glycogen synthase D and maximum Vmax for the reaction with phosphorylase a.
已报道了一种从兔心脏中纯化作用于肌肉磷酸化酶a的低分子量磷蛋白磷酸酶的简化方法。通过酸沉淀、乙醇处理以及在葡聚糖凝胶G - 75和琼脂糖 - 组蛋白上进行层析，将该酶纯化至同质。用十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳检测时，纯化后的酶呈现出一条带；用此方法计算出的分子量为34000。该酶的S20,W值和斯托克斯半径分别为3.35和24.0 Å（1 Å = 0.1 nm）。利用这两个值计算出分子量为35000。纯化后的酶表现出广泛的底物特异性，可催化磷酸化酶a、糖原合酶D、磷酸化组蛋白和磷酸化酪蛋白的去磷酸化反应。动力学研究表明，与糖原合酶D反应时Km最低，与磷酸化酶a反应时Vmax最大。
