1kuf
From Proteopedia
High-resolution Crystal Structure of a Snake Venom Metalloproteinase from Taiwan Habu
Structural highlights
Function[VM2T3_PROMU] Snake venom metalloproteinase TM-3: fibrin(ogen)olytic protease which cleaves the Aalpha chain of fibrinogen (FGA) first followed by the Bbeta chain (FGB) and shows relatively low activity on the gamma chain (FGG).[1] [2] Disintegrin trimucrin: inhibits platelet aggregation induced by ADP, thrombin, platelet-activating factor and collagen. Acts by inhibiting fibrinogen interaction with platelet receptors GPIIb/GPIIIa (ITGA2B/ITGB3).[3] [4] 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 PubMedThe crystal structure of TM-3, a small snake-venom metalloproteinase (SVMP) isolated from Taiwan habu (Trimeresurus mucrosquamatus), was determined at 1.35 A resolution with resultant R and R(free) values of 0.181 and 0.204, respectively. The overall structure of TM-3 is an oblate ellipsoid that contains three disulfide crosslinks, Cys118-Cys197, Cys159-Cys181 and Cys161-Cys164. It exhibits the typical structural features of SVMPs and is closely related to the structure of the catalytic proteinase domain of TNFalpha-converting enzyme (TACE). In the present structure, the essential catalytic zinc ion was found to be replaced by a cadmium ion during crystallization, as revealed by atomic absorption analysis and X-ray data. This cadmium ion is bound to six ligands, including three conserved histidines and three water molecules, displaying the coordination geometry of a distorted octahedron. One of the water molecules is proposed to play the role of stabilizing the tetrahedral intermediate during the catalysis of SVMPs. The putative S'(1) specificity pocket of TM-3 is relatively shallow, in contrast to the deep pockets of adamalysin II, atrolysin C and H(2)-proteinase, but is similar to those in acutolysin A and TACE. The shallow pocket is a consequence of the presence of the non-conserved disulfide bond Cys159-Cys181 and the residue Gln174 at the bottom of the S'(1) pocket. The results indicate that the active-site structure of TM-3, among the know structures of SVMPs examined thus far, is most similar to that of TACE owing to their close disulfide configurations and the S'(1) specificity pocket. The 1.35 A structure of cadmium-substituted TM-3, a snake-venom metalloproteinase from Taiwan habu: elucidation of a TNFalpha-converting enzyme-like active-site structure with a distorted octahedral geometry of cadmium.,Huang KF, Chiou SH, Ko TP, Yuann JM, Wang AH Acta Crystallogr D Biol Crystallogr. 2002 Jul;58(Pt 7):1118-28. Epub 2002, Jun 20. PMID:12077431[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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