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1alj

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[[Image:1alj.gif|left|200px]]
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{{STRUCTURE_1alj| PDB=1alj | SCENE= }}
{{STRUCTURE_1alj| PDB=1alj | SCENE= }}
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'''ALKALINE PHOSPHATASE MUTANT (H412N)'''
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===ALKALINE PHOSPHATASE MUTANT (H412N)===
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==Overview==
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The X-ray structure of a mutant version of Escherichia coli alkaline phosphatase (H412N) in which His-412 was replaced by Asn has been determined at both low (-Zn) and high (+Zn) concentrations of zinc. In the wild-type structure, His-412 is a direct ligand to one of the two catalytically critical zinc atoms (Zn1) in the active site. Characterization of the H412N enzyme in solution revealed that the mutant enzyme required high concentrations of zinc for maximal activity and for high substrate and phosphate affinity (Ma L, Kantrowitz ER, 1994, J Biol Chem 269:31614-31619). The H412N enzyme was also inhibited by Tris, in contrast to the wild-type enzyme, which is activated more than twofold by 1 M Tris. To understand these kinetic properties at the molecular level, the structure of the H412N (+Zn) enzyme was refined to an R-factor of 0.174 at 2.2 A resolution, and the structure of the H412N(-Zn) enzyme was refined to an R-factor of 0.166 at a resolution of 2.6 A. Both indicated that the Asn residue substituted for His-412 did not coordinate well to Zn1. In the H412N(-Zn) structure, the Zn1 site had very low occupancy and the phosphate was shifted by 1.8 A from its position in the wild-type structure. The Mg binding site was also affected by the substitution of Asn for His-412. Both structures of the H412N enzyme also revealed a surface-accessible cavity near the Zn1 site that may serve as a binding site for Tris.(ABSTRACT TRUNCATED AT 250 WORDS)
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{{ABSTRACT_PUBMED_8520475}}
==About this Structure==
==About this Structure==
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[[Category: Ma, L.]]
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[[Category: Tibbitts, T T.]]
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Revision as of 14:06, 30 June 2008

Image:1alj.png

Template:STRUCTURE 1alj

ALKALINE PHOSPHATASE MUTANT (H412N)

Template:ABSTRACT PUBMED 8520475

About this Structure

1ALJ is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Escherichia coli alkaline phosphatase: X-ray structural studies of a mutant enzyme (His-412-->Asn) at one of the catalytically important zinc binding sites., Ma L, Tibbitts TT, Kantrowitz ER, Protein Sci. 1995 Aug;4(8):1498-506. PMID:8520475

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