1y7a
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(New page: 200px<br /><applet load="1y7a" size="450" color="white" frame="true" align="right" spinBox="true" caption="1y7a, resolution 1.77Å" /> '''Structure of D153H/K...)
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Revision as of 04:29, 21 November 2007
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Structure of D153H/K328W E. coli alkaline phosphatase in presence of cobalt at 1.77 A resolution
Overview
Escherichia coli alkaline phosphatase exhibits maximal activity when, Zn(2+) fills the M1 and M2 metal sites and Mg(2+) fills the M3 metal site., When other metals replace the zinc and magnesium, the catalytic efficiency, is reduced by more than 5000-fold. Alkaline phosphatases from organisms, such as Thermotoga maritima and Bacillus subtilis require cobalt for, maximal activity and function poorly with zinc and magnesium. Previous, studies have shown that the D153H alkaline phosphatase exhibited very, little activity in the presence of cobalt, while the K328W and especially, the D153H/K328W mutant enzymes can use cobalt for catalysis. To understand, the structural basis for the altered metal specificity and the ability of, the D153H/K328W enzyme to utilize cobalt for catalysis, we determined the, structures of the inactive wild-type E. coli enzyme with cobalt (WT_Co), and the structure of the active D153H/K328W enzyme with cobalt (HW_Co)., The structural data reveal differences in the metal coordination and in, the strength of the interaction with the product phosphate (P(i)). Since, release of P(i) is the slow step in the mechanism at alkaline pH, the, enhanced binding of P(i) in the WT_Co structure explains the observed, decrease in activity, while the weakened binding of P(i) in the HW_Co, structure explains the observed increase in activity. These alterations in, P(i) affinity are directly related to alterations in the coordination of, the metals in the active site of the enzyme.
About this Structure
1Y7A is a Single protein structure of sequence from Escherichia coli with CO, PO4 and SO4 as ligands. Active as Alkaline phosphatase, with EC number 3.1.3.1 Full crystallographic information is available from OCA.
Reference
Metal specificity is correlated with two crucial active site residues in Escherichia coli alkaline phosphatase., Wang J, Stieglitz KA, Kantrowitz ER, Biochemistry. 2005 Jun 14;44(23):8378-86. PMID:15938627
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