Conformational similarities between one-chain and two-chain tissue plasminogen activator (t-PA): implications to the activation mechanism on one-chain t-PA.
Conformational similarities between one-chain and two-chain tissue plasminogen activator (t-PA): implications to the activation mechanism on one-chain t-PA.
复制标题
单链和双链组织纤溶酶原激活剂 (t-PA) 之间的构象相似性：对单链 t-PA 激活机制的影响。
DOI：
10.1021/bi00130a017
复制
发表时间：
1992
期刊：
影响因子：
2.9
通讯作者：
Berliner,LJ
中科院分区：
文献类型：
--
作者：
Nienaber,VL;Young,SL;Birktoft,JJ;Higgins,DL;Berliner,LJ
Revised Manuscript Received January 30, 1992 abstract: Tissue plasminogen activator (t-PA) is an exceptional serine protease, because unlike most other serine protease zymogens single-chain tissue plasminogen activator (sct-PA) possesses a substantial amount of proteolytic activity. The unusual reaction of sct-PA afforded the opportunity to directly compare the active site environment of sct-PA and two-chain tissue plasminogen activator (tct-PA) insolution through the application of a series of nitroxide spin labels and fluorophores. These labels, which have been previously shown to covalently label the catalytic serine of other serine proteases, inactivated both sct-PA and tct-PA. The labels can be divided into two classes: those which form tetrahedral complexes (sulfonates) and those which form trigonal complexes (anthranilates). Those which formed tetrahedral complexes were found to be insensitiveto structural differences between sct-PA and tct-PA at the active site. In contrast, those which formed trigonal complexes could differentiate and monitor the sct-PA to tct-PA conversion by fluorescence spectroscopy. Models of the structure of sct-PA and tct-PA were constructed on the basis of the known X-ray structures of other serine protease zymogen and active enzyme forms. One of the nitroxide spin labels was modeled into the sct-PA and tct-PA structures in two possible orientations, both of which could be sensitive to structural differences between sct-PA and tct-PA. These models formed the structural rationale used to explain the results obtained with the “tetrahedral” and “trigonal” probes, as well as to offer a possible explanation for the unique reactivity of sct-PA. e enzymes of the mammalian serine protease family, ie, trypsin, chymotrypsin, and elastase, are highly homologous in structure and catalytic mechanism. In addition, most of these enzymes are biosynthesized asa single-chain proenzyme or zymogen which is almost entirely devoid of enzymatic ac-tivity. The inactive zymogen formof all of these proteins requires activation via limited proteolysis in order to yield significant amounts of enzyme activity. The activation of
