Kominami E, Wakamatsu N, Katunuma N
J Biol Chem. 1982 Dec 25;257(24):14648-52.
A thiol proteinase inhibitor was purified from rat liver by essentially the same procedure as reported previously (Kominami, E., Wakamatsu, N., and Katunuma, N. (1981) Biochem. Biophys. Res. Commun. 99, 568-575), but without heat treatment. The purified inhibitor appears homogeneous on polyacrylamide gel electrophoresis with and without sodium dodecyl sulfate and displayed no multiple forms. The inhibitor has Mr = 12,500 and contains 50.5% of polar amino acid residues, 9.3% aromatic amino acids, and no tryptophan. The presence of 2 half-cystines/molecule and the absence of free thiol groups indicate that the inhibitor possesses one disulfide bridges. The inhibitor inhibits cathepsin H by forming an enzyme-inhibitor complex in a molar ratio of 1:1. It inhibits most thiol proteinases such as cathepsin H, L, B, and C, papain, and ficin, but not calcium-activated neutral proteinase or serine proteinases or carboxyl proteinases. The inhibitor was found in various rat tissues. Immunological diffusion analysis with anti-liver thiol proteinase inhibitor serum indicated that the rat liver inhibitor is immunologically identical with the inhibitors from other rat tissues. On subcellular fractionation of rat liver, the thiol proteinase inhibitor was recovered in the cytosol fraction.
采用与之前报道的基本相同的方法（小南英夫、若松直、葛沼努马，《生物化学与生物物理学研究通讯》，第99卷，第568 - 575页，1981年）从大鼠肝脏中纯化出一种巯基蛋白酶抑制剂，但未进行热处理。纯化后的抑制剂在有无十二烷基硫酸钠的聚丙烯酰胺凝胶电泳上均呈现均一性，且未显示出多种形式。该抑制剂的相对分子质量为12,500，含有50.5%的极性氨基酸残基、9.3%的芳香族氨基酸，且不含色氨酸。每个分子中存在2个半胱氨酸且不存在游离巯基，这表明该抑制剂具有一个二硫键。该抑制剂通过以1:1的摩尔比形成酶 - 抑制剂复合物来抑制组织蛋白酶H。它能抑制大多数巯基蛋白酶，如组织蛋白酶H、L、B和C、木瓜蛋白酶和无花果蛋白酶，但不抑制钙激活中性蛋白酶、丝氨酸蛋白酶或羧基蛋白酶。在大鼠的各种组织中都发现了这种抑制剂。用抗肝脏巯基蛋白酶抑制剂血清进行免疫扩散分析表明，大鼠肝脏抑制剂与来自其他大鼠组织的抑制剂在免疫上是相同的。对大鼠肝脏进行亚细胞分级分离时，巯基蛋白酶抑制剂存在于胞质溶胶组分中。
