Cathepsin H: an endoaminopeptidase from rat liver lysosomes.
Cathepsin H: an endoaminopeptidase from rat liver lysosomes.
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发表时间：
1977
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通讯作者：
H. Kirschke;J. Langner;B. Wiederanders;S. Ansorge;P. Bohley;H. Hanson
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作者：
H. Kirschke;J. Langner;B. Wiederanders;S. Ansorge;P. Bohley;H. Hanson
1.组织蛋白酶H是属于巯基酶组的内氨基肽酶。经Sephadex G-75凝胶过滤、CM-Sephadex C-50层析、DEAE-Cellulose DE-52层析和有机汞吸附剂层析，从大鼠肝溶酶体中纯化得到。2.发现组织蛋白酶H的分子量为28，000，并且通过分析等电聚焦估计等电点为pH 7.1。3.组织蛋白酶H必须指定为内氨基肽酶，因为它分别催化蛋白质、N-末端取代蛋白质和氨基酸衍生物的水解，以及各种链长的肽和N-末端游离氨基酸衍生物的水解。组织蛋白酶H显示酰胺酶和酯酶活性，但不显示羧肽酶活性。组织蛋白酶H的氨基和内肽酶性质的发现主要是由抑制剂的结果和该酶相当高的温度稳定性所揭示的。亮氨酸的氯甲基酮被证明是氨肽酶和内肽酶活性的最强抑制剂，而亮肽素内肽酶活性和内肽酶底物竞争性地抑制氨肽酶活性。5.组织蛋白酶H在pH6.0，1- 5 mM GSH和EDTA存在下显示最高活性。6.该酶在深度冷冻状态下在微酸性pH值下稳定数月。
1. Cathepsin H is an endoaminopeptidase belonging to the group of thiol enzymes. It was purified from rat liver lysosomes by gel filtration on Sephadex G-75, chromatography on CM-Sephadex C-50, on DEAE-Cellulose DE-52 and subsequently on an organomercurial absorbent. 2. The molecular weight of cathepsin H was found to be 28,000 and the isoelectric point was estimated to be at pH 7.1 by analytical isoelectric focusing. 3. Cathepsin H has to be designated as endoaminopeptidase, because it catalyzes the hydrolysis of proteins, N-terminal substituted proteins and amino acid derivatives, respectively, as well as of peptides of various chain length and N-terminal free amino acid derivatives. Cathepsin H shows amidase and esterase activity, but it does not show carboxypeptidase activity. The finding of the amino- and endopeptidase nature of cathepsin H has been revealed mainly by the results obtained with inhibitors and by the rather high temperature stability of the enzyme. The chlormethyl ketone of leucine proves to be the strongest inhibitor of the aminopeptidase as well as of the endopeptidase activity, whereas leupeptin endopeptidase activity and endopeptidase substrates inhibit competitively the aminopeptidase activity. 5. Cathepsin H shows highest activity at pH 6.0 in the presence of 1--5 mM GSH and EDTA. 6. The enzyme is stable for several months at slightly acid pH values in a deep frozen state.