MULTIPLE-MODES OF ACTIVATION OF LATENT HUMAN FIBROBLAST COLLAGENASE - EVIDENCE FOR THE ROLE OF A CYS-73 ACTIVE-SITE ZINC COMPLEX IN LATENCY AND A CYSTEINE SWITCH MECHANISM FOR ACTIVATION
MULTIPLE-MODES OF ACTIVATION OF LATENT HUMAN FIBROBLAST COLLAGENASE - EVIDENCE FOR THE ROLE OF A CYS-73 ACTIVE-SITE ZINC COMPLEX IN LATENCY AND A CYSTEINE SWITCH MECHANISM FOR ACTIVATION
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DOI：
10.1073/pnas.87.1.364
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发表时间：
1990-01-01
影响因子：
11.1
通讯作者：
VANWART, HE
中科院分区：
文献类型：
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作者：
SPRINGMAN, EB;ANGLETON, EL;VANWART, HE
潜伏的人成纤维细胞胶原酶(HFC)可以通过各种看似不同的方式被激活。除了被胰酶和有机汞化合物激活外，该酶还可以被表面活性剂(如十二烷基硫酸钠)、热致离子(如SCN-)、二硫化物(如氧化谷胱甘肽)、巯基烷基化试剂(如N-乙基马来酰亚胺)和氧化剂(如NaOCl)激活。这些激活的基本基础是Cys73残基的修饰、暴露或蛋白水解性释放，这些残基从其在潜伏酶中的栖息地被认为与活性部位的锌原子络合。在天然的潜伏性HFC中，这种残留物不能与小摩尔过量的二硫代硝基苯甲酸盐反应。然而，一旦加入EDTA，这个残基就会完全暴露并被定量标记。潜伏的HFC的所有激活模式都被认为涉及到Cys73从活性中心锌原子上解离并被水取代，并伴随着活性中心的暴露。这被认为是胶原酶活性出现后观察到的众所周知的自溶切割之前的主要事件。Cys73从潜伏酶中的锌原子解离，将锌的作用从非催化作用“切换”为催化作用。这种“半胱氨酸开关”的调节机制可能适用于整个胶原酶基因家族。
Latent human fibroblast collagenase (HFC) can be activated by a variety of seemingly disparate means. In addition to the well-characterized activation by trypsin and organomercurial compounds, the enzyme can be activated to various extents by surfactants such as sodium dodecyl sulfate, by chaotropic ions such as SCN-, by disulfide compounds such as oxidized glutathione, by sulfhydryl alkylating agents such as N-ethylmaleimide, and by oxidants such as NaOCl. The underlying basis for these activations is the modification, exposure, or proteolytic release of the Cys73 residue from its habitat in the latent enzyme where it is thought to be complexed to the active-site zinc atom. This residue is not accessible for reaction with small molar excesses of dithionitrobenzoate in native, latent HFC. However, on addition of EDTA, this residue becomes fully exposed and is quantitatively labeled. All modes of activation of latent HFC are believed to involve the dissociation of Cys73 from the active-site zinc atom and its replacement by water, with the concomitant exposure of the active site. This is thought to be the primary event that precedes the well-known autolytic cleavages that are observed following the appearance of collagenase activity. The dissociation of Cys73 from the zinc atom in the latent enzyme "switches" the role of the zinc from a noncatalytic to a catalytic one. This "cysteine switch" mechanism of regulation may be applicable to the entire collagenase gene family.