1ane
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(New page: 200px<br /><applet load="1ane" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ane, resolution 2.2Å" /> '''ANIONIC TRYPSIN WILD ...)
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Revision as of 08:51, 20 November 2007
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ANIONIC TRYPSIN WILD TYPE
Overview
The X-ray crystal structure of the copper complex of the rat trypsin, mutant Arg96 to His96 (trypsin R96H) has been determined in order to, ascertain the nature of the engineered metal-binding site and to, understand the structural basis for the metal-induced enzymatic, inhibition. In the structure, the catalytically essential His57 residue is, reoriented out of the active-site pocket and forms a chelating, metal-binding site with residue His96. The copper is bound to the N, epsilon 2 atoms of both histidine residues with Cu-N epsilon 2 = 2.2 A and, N epsilon 2-Cu-N epsilon 2 = 89 degrees. The metal is clearly bound to a, third ligand leading to a distorted square planar geometry at Cu. The, X-ray results do not unambiguously yield the identity of this third, ligand, but chemical data suggest that it is a deprotonated, chelating, Tris molecule which was used as a carrier to solubilize the copper in, alkaline solution (pH 8.0). Upon reorientation of His57, a unique water, molecule moves into the active site and engages in hydrogen-bonding with, Asp102-O delta 2 and His57-N delta 1. Except for small movements of the, peptide backbone near His96, the remainder of the trypsin molecule is, isostructural with the native enzyme. These data support the notion that, the effective inhibition of catalytic activity by metal ions observed in, trypsin R96H is indeed caused by a specific and reversible reorganization, of the active site in the enzyme.
About this Structure
1ANE is a Single protein structure of sequence from Rattus rattus with BEN as ligand. Active as Trypsin, with EC number 3.4.21.4 Full crystallographic information is available from OCA.
Reference
Structure of an engineered, metal-actuated switch in trypsin., McGrath ME, Haymore BL, Summers NL, Craik CS, Fletterick RJ, Biochemistry. 1993 Mar 2;32(8):1914-9. PMID:8448149
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