1rtf
COMPLEX OF BENZAMIDINE WITH THE CATALYTIC DOMAIN OF HUMAN TWO CHAIN TISSUE PLASMINOGEN ACTIVATOR [(TC)-T-PA]
Structural highlights
DiseaseTPA_HUMAN Note=Increased activity of TPA results in increased fibrinolysis of fibrin blood clots that is associated with excessive bleeding. Defective release of TPA results in hypofibrinolysis that can lead to thrombosis or embolism. FunctionTPA_HUMAN Converts the abundant, but inactive, zymogen plasminogen to plasmin by hydrolyzing a single Arg-Val bond in plasminogen. By controlling plasmin-mediated proteolysis, it plays an important role in tissue remodeling and degradation, in cell migration and many other physiopathological events. Plays a direct role in facilitating neuronal migration. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTissue-type plasminogen activator (t-PA), a multidomainal serine proteinase of the trypsin-family, catalyses the rate-limiting step in fibrinolysis, the activation of plasminogen to the fibrin-degrading proteinase plasmin. Trigonal crystals have been obtained of the recombinant catalytic domain of human-two-chain t-PA, consisting of a 17 residue A chain and the 252 residue B chain. Its X-ray crystal structure has been solved applying Patterson and isomorphous replacement methods, and has been crystallographically refined to an R-value of 0.184 at 2.3 A resolution. The chain fold, active-site geometry and Ile276-Asp477 salt bridge are similar to that observed for trypsin. A few surface-located insertion loops differ significantly, however. The disulfide bridge Cys315-Cys384, practically unique to the plasminogen activators, is incorporated without drastic conformational changes as the insertion loop preceding Cys384 makes a bulge on the molecular surface. The unique basic insertion loop Lys296-Arg304 flanking the primed subsites, which has been shown to be of importance for PAI-1 binding and for fibrin specificity, is partially disordered; it can therefore freely adapt to proteins docking to the active site. The S1 pocket of t-PA is almost identical to that of trypsin, whereas the S2 site is considerably reduced in size by the imposing Tyr368 side-chain, in agreement with the measured preference for P1 Arg and P2 Gly residues. The neighbouring S3-S4 hydrophobic groove is mainly hydrophobic in nature. The structure of the proteinase domain of two-chain t-PA suggests that the formation of a salt bridge between Lys429 and Asp477 may contribute to the unusually high catalytic activity of single-chain t-PA, thus stabilizing the catalytically active conformation without unmasking the Ile276 amino terminus. Modeling studies show that the covalently bound kringle 2 domain in full-length t-PA could interact with an extended hydrophobic groove in the catalytic domain; in such a docking geometry its "lysine binding site" and the "fibrin binding patch" of the catalytic domain are in close proximity. The 2.3 A crystal structure of the catalytic domain of recombinant two-chain human tissue-type plasminogen activator.,Lamba D, Bauer M, Huber R, Fischer S, Rudolph R, Kohnert U, Bode W J Mol Biol. 1996 Apr 26;258(1):117-35. PMID:8613982[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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