Suzuki K, Siddique T, Ohya S, Kaneko M, Maruyama S, Shoji S, Uyeda M
Faculty of Pharmaceutical Science, Kumamoto University, Japan.
J Enzyme Inhib. 1996;10(3):177-86. doi: 10.3109/14756369609030311.
S-PLI, an inhibitor of phospholipase C (PLC) produced by Streptomyces sp. strain No. 6288, was purified from the culture filtrate by salting-out with solid ammonium sulfate, column chromatography on CM-cellulose and gel filtration on Sephadex G-75. The molecular weight of S-PLI was estimated to be 65,000 by SDS-polyacrylamide gel electrophoresis. The inhibitor was found to be a glycoprotein with a composition of 609 amino acids and 19 glucose residues having an isoelectric point at 7.8. S-PLI was stable from pH 3 to 10 at 37 degrees C and up to 40 degrees at pH 6.0. The inhibitory activity showed pH- and temperature-dependence with a maximum around pH 7.0 at 50 degrees C. S-PLI inhibited phospholipase C in a competitive manner (Ki value; 9.5 x 10(-6) mM), but did not inhibit S-Hemolysin, phospholipase A2; phospholipase B, phospholipase D and phosphatases. S-PLI is the first reported example of a glycoproteinaceous inhibitor of microbial origin which is able to specifically inhibit phospholipase C.
S-PLI是由链霉菌属6288号菌株产生的一种磷脂酶C（PLC）抑制剂，通过用固体硫酸铵盐析、CM-纤维素柱色谱和Sephadex G-75凝胶过滤从培养滤液中纯化得到。通过SDS-聚丙烯酰胺凝胶电泳估计S-PLI的分子量为65,000。该抑制剂被发现是一种糖蛋白，由609个氨基酸和19个葡萄糖残基组成，等电点为7.8。S-PLI在37℃下pH值为3至10时稳定，在pH 6.0时高达40℃仍稳定。抑制活性表现出pH和温度依赖性，在50℃、pH 7.0左右达到最大值。S-PLI以竞争性方式抑制磷脂酶C（Ki值；9.5×10⁻⁶ mM），但不抑制S-溶血素、磷脂酶A2、磷脂酶B、磷脂酶D和磷酸酶。S-PLI是首次报道的微生物来源的能够特异性抑制磷脂酶C的糖蛋白类抑制剂。
