Surface acid proteinase (gp63) of Leishmania mexicana. A metalloenzyme capable of protecting liposome-encapsulated proteins from phagolysosomal degradation by macrophages.
Surface acid proteinase (gp63) of Leishmania mexicana. A metalloenzyme capable of protecting liposome-encapsulated proteins from phagolysosomal degradation by macrophages.
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发表时间：
1989-05
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通讯作者：
G. Chaudhuri;Minu Chaudhuri;A. Pan;K. Chang
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作者：
G. Chaudhuri;Minu Chaudhuri;A. Pan;K. Chang
酸性蛋白酶活性与寄生原生动物墨西哥利什曼原虫的细胞外前鞭毛体和细胞内无鞭毛体的主要表面糖蛋白（gp 63）相关。通过单克隆亲和色谱法从前鞭毛体纯化的酶被金属离子螯合剂强烈抑制，这是可逆的，通过添加Zn（II）。这种蛋白酶在对1，10-菲咯啉透析后失去活性。由此制备的脱辅基酶基本上被Zn（II）和部分地被Cu（II）、Cd（II）、Co（II）或Ni（II）再活化。从最近发表的结构的基因编码的gp 63，我们确定迄今未被识别的序列，它可以对齐的共识锌结合位点的其他已知的金属蛋白酶。抗gp 63多克隆抗体，而不是单克隆抗体，沉淀类似的分子从无鞭毛体。这些分子在电泳迁移率上与gp 63略有不同，但具有相似的内肽酶活性。用天然gp 63包被脂质体可防止脂质体中包埋的蛋白质被巨噬细胞吞噬溶酶体降解。这种保护作用随着gp 63的热变性而丧失，从而杀死其酶活性。因此，这些寄生虫表面的金属酶的蛋白水解活性可以保护它们的膜在巨噬细胞的吞噬溶酶体中的存活、分化和增殖期间免受细胞溶解性损伤。
Acid proteinase activity is associated with the major surface glycoprotein (gp63) of both extracellular promastigotes and intracellular amastigotes of the parasitic protozoan, Leishmania mexicana. The enzyme purified by monoclonal affinity chromatography from promastigotes is strongly inhibited by metal ion chelators, which is reversible by the addition of Zn(II). This proteinase loses its activity after dialysis against 1,10-phenanthroline. The apoenzyme thus prepared is reactivated substantially by Zn(II) and partially by Cu(II), Cd(II), Co(II), or Ni(II). From the recently published structure of the gene encoding gp63, we identify hitherto unrecognized sequences, which can be aligned to the consensus zinc-binding sites of other known metalloproteinases. Anti-gp63 polyclonal antibodies, but not the monoclonals, precipitate similar molecules from amastigotes. These molecules differ slightly from gp63 in electrophoretic mobility but have similar endopeptidase activity. Phagolysosomal degradation by macrophages of proteins entrapped in liposomes is prevented by coating them with native gp63. This protection is lost with heat denaturation of gp63 to kill its enzymatic activity. The proteolytic activity of the metalloenzyme on the surface of these parasites may thus protect their membrane from cytolytic damages during their survival, differentiation, and multiplication in the phagolysosomes of macrophages.