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1wcq

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[[Image:1wcq.gif|left|200px]]
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{{STRUCTURE_1wcq| PDB=1wcq | SCENE= }}
{{STRUCTURE_1wcq| PDB=1wcq | SCENE= }}
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'''MUTAGENESIS OF THE NUCLEOPHILIC TYROSINE IN A BACTERIAL SIALIDASE TO PHENYLALANINE.'''
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===MUTAGENESIS OF THE NUCLEOPHILIC TYROSINE IN A BACTERIAL SIALIDASE TO PHENYLALANINE.===
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==Overview==
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Mutants of the Micromonospora viridifaciens sialidase, Y370E and Y370F, are catalytically active retaining enzymes that operate by different mechanisms. Previous substitutions with smaller amino acids, including Y370D, yielded inverting sialidases. At least one water molecule can fit into the active-site cavity of this mutant and act as a nucleophile from the face opposite the leaving group (Biochemistry 2003, 42, 12 682). Thus, addition of a CH(2) unit (Asp versus Glu) changes the mechanism from inversion back to retention of configuration. Based on Bronsted beta(lg) values, it is proposed that the Y370E mutant reacts by a double-displacement mechanism (beta(lg) on k(cat)/K(m) -0.36+/-0.04) with Glu370 acting as the nucleophile. However, the Y370F mutant (beta(lg) on k(cat)/K(m) -0.79+/-0.12) reacts via a dissociative transition state. The crystal structure of the Y370F mutant complexed with 2-deoxy-2,3-dehydro-N-acetylneuraminic acid shows no significant active-site perturbation relative to the wild-type enzyme.
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(as it appears on PubMed at http://www.pubmed.gov), where 16206228 is the PubMed ID number.
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{{ABSTRACT_PUBMED_16206228}}
==About this Structure==
==About this Structure==
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[[Category: Micromonospora viridifacien]]
[[Category: Micromonospora viridifacien]]
[[Category: Sialidase]]
[[Category: Sialidase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 13:28:33 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 13:08:26 2008''

Revision as of 10:08, 29 July 2008

Image:1wcq.png

Template:STRUCTURE 1wcq

MUTAGENESIS OF THE NUCLEOPHILIC TYROSINE IN A BACTERIAL SIALIDASE TO PHENYLALANINE.

Template:ABSTRACT PUBMED 16206228

About this Structure

1WCQ is a Single protein structure of sequence from Micromonospora viridifaciens. Full crystallographic information is available from OCA.

Reference

Two nucleophilic mutants of the Micromonospora viridifaciens sialidase operate with retention of configuration by two different mechanisms., Watson JN, Newstead S, Narine AA, Taylor G, Bennet AJ, Chembiochem. 2005 Nov;6(11):1999-2004. PMID:16206228

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