1h2g

Altered substrate specificity mutant of penicillin acylaseAltered substrate specificity mutant of penicillin acylase

Structural highlights 1h2g is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PAC_ECOLX 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 PubMed Two mutant forms of penicillin acylase from Escherichia coli strains, selected using directed evolution for the ability to use glutaryl-L-leucine for growth [Forney, Wong and Ferber (1989) Appl. Environ. Microbiol. 55, 2550-2555], are changed within one codon, replacing the B-chain residue Phe(B71) with either Cys or Leu. Increases of up to a factor of ten in k (cat)/ K (m) values for substrates possessing a phenylacetyl leaving group are consistent with a decrease in K (s). Values of k (cat)/ K (m) for glutaryl-L-leucine are increased at least 100-fold. A decrease in k (cat)/ K (m) for the Cys(B71) mutant with increased pH is consistent with binding of the uncharged glutaryl group. The mutant proteins are more resistant to urea denaturation monitored by protein fluorescence, to inactivation in the presence of substrate either in the presence of urea or at high pH, and to heat inactivation. The crystal structure of the Leu(B71) mutant protein, solved to 2 A resolution, shows a flip of the side chain of Phe(B256) into the periphery of the catalytic centre, associated with loss of the pi-stacking interactions between Phe(B256) and Phe(B71). Molecular modelling demonstrates that glutaryl-L-leucine may bind with the uncharged glutaryl group in the S(1) subsite of either the wild-type or the Leu(B71) mutant but with greater potential freedom of rotation of the substrate leucine moiety in the complex with the mutant protein. This implies a smaller decrease in the conformational entropy of the substrate on binding to the mutant proteins and consequently greater catalytic activity. Mutations of penicillin acylase residue B71 extend substrate specificity by decreasing steric constraints for substrate binding.,Morillas M, McVey CE, Brannigan JA, Ladurner AG, Forney LJ, Virden R Biochem J. 2003 Apr 1;371(Pt 1):143-50. PMID:12511194 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Penicillin acylase

spinqualitylabelsall models 1h2g, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image