2gds
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(New page: 200px<br /> <applet load="2gds" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gds, resolution 2.30Å" /> '''Interrupting the Hy...)
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Revision as of 20:11, 12 November 2007
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Interrupting the Hydrogen Bonding Network at the Active Site of Human Manganese Superoxide Dismutase
Overview
Histidine 30 in human manganese superoxide dismutase (MnSOD) is located at, a site partially exposed to solvent with its side chain participating in a, hydrogen-bonded network that includes the active-site residues Tyr(166), and Tyr(34) and extends to the manganese-bound solvent molecule. We have, replaced His(30) with a series of amino acids and Tyr(166) with Phe in, human MnSOD. The crystal structure of the mutant of MnSOD containing, Asn(30) superimposed closely with the wild type, but the side chain of, Asn(30) did not participate in the hydrogen-bonded network in the active, site. The catalytic activity of a number of mutants with replacements at, position 30 and for the mutant containing Phe(166) showed a 10-40-fold, decrease in k(cat). This is the same magnitude of decrease in k(cat), obtained with the replacement of Tyr(34) by Phe, suggesting that, interrupting the hydrogen-bonded active-site network at any of the sites, of these three participants (His(30), Tyr(34), and Tyr(166)) leads to an, equivalent decrease in k(cat) and probably less efficient proton transfer, to product peroxide. The specific geometry of His(30) on the hydrogen bond, network is essential for stability since the disparate mutations H30S, H30A, and H30Q reduce T(m) by similar amounts (10-16 degrees C) compared, with wild type.
About this Structure
2GDS is a Single protein structure of sequence from Homo sapiens with MN as ligand. Active as Superoxide dismutase, with EC number 1.15.1.1 Full crystallographic information is available from OCA.
Reference
Interrupting the hydrogen bond network at the active site of human manganese superoxide dismutase., Ramilo CA, Leveque V, Guan Y, Lepock JR, Tainer JA, Nick HS, Silverman DN, J Biol Chem. 1999 Sep 24;274(39):27711-6. PMID:10488113
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