Schwartz W N, Barrett A J
Biochem J. 1980 Nov 1;191(2):487-97. doi: 10.1042/bj1910487.
Cathepsin H was purified from human liver by a method involving autolysis and acetone fractionation, and chromatography on DEAE-cellulose, Ultrogel AcA 54, hydroxyapatite and concanavalin A-Sepharose. The procedure allowed for the simultaneous isolation of cathepsin B and cathepsin D. Cathepsin H was shown to consist of a single polypeptide chain of 28 000 mol.wt., and affinity for concanavalin A-Sepharose indicated that it was a glycoprotein. The enzyme existed in multiple isoelectric forms, the two major forms having pI values of 6.0 and 6.4; it hydrolysed azocasein (pH optimum 5.5), benzoylarginine 2-naphthylamide (Ba-Arg-NNap), leucyl 2-naphthylamide (Arg-NNap), (pH optimum 6.8). Arg-NNap and Arg-NMec, unlike Bz-Arg-NNap-, were not hydrolysed by human cathepsin B. Cathepsin H was similar to cathepsin B in being irreversibly inactivated by exposure to alkaline pH. Sensitivity to chemical inhibitors by 1 microM-leupeptin, which gave essentially complete inhibition of the other lysosomal cysteine proteinases, cathepsins B and L.
组织蛋白酶H是通过一种包括自溶、丙酮分级分离以及在DEAE-纤维素、超凝胶AcA 54、羟基磷灰石和伴刀豆球蛋白A-琼脂糖上进行色谱分离的方法从人肝脏中纯化得到的。该方法还能同时分离出组织蛋白酶B和组织蛋白酶D。组织蛋白酶H显示为由一条分子量为28000的单多肽链组成，并且对伴刀豆球蛋白A-琼脂糖的亲和力表明它是一种糖蛋白。该酶存在多种等电形式，两种主要形式的pI值分别为6.0和6.4；它能水解偶氮酪蛋白（最适pH 5.5）、苯甲酰精氨酸2-萘酰胺（Ba-Arg-NNap）、亮氨酰2-萘酰胺（Leu-NNap）（最适pH 6.8）。与Bz-Arg-NNap不同，Arg-NNap和Arg-NMec不会被人组织蛋白酶B水解。组织蛋白酶H与组织蛋白酶B相似，暴露于碱性pH下会不可逆地失活。对1 microM亮抑酶肽这种化学抑制剂敏感，亮抑酶肽能基本完全抑制其他溶酶体半胱氨酸蛋白酶，即组织蛋白酶B和组织蛋白酶L。
