1q4n

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{{STRUCTURE_1q4n| PDB=1q4n | SCENE= }}
{{STRUCTURE_1q4n| PDB=1q4n | SCENE= }}
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'''Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity'''
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===Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity===
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==Overview==
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In the mechanism of hydrolysis of starch by alpha-amylases, a conserved water molecule bridging two catalytic residues has been implicated. In human salivary alpha-amylase (HSAmy), this water (W641), observed in many alpha-amylase structures, is part of a chain of water molecules. To test the hypothesis that W641 may be involved in the mechanism, Phe256 in the close vicinity was mutated to a Trp residue. X-ray structure of F256W complexed to 2-amino-2-(hydroxyethyl)-1,3-propanediol at 2.1A revealed that the water chain is disrupted. In the F256W structure exhibits a positional shift in His305, characteristic of alpha-amylase complex structures. Kinetic analysis, in comparison with HSAmy, revealed that the mutant exhibited a 70-fold decrease in the specific activity for starch and significantly reduced k(cat) (20-fold) and K(m) (4-fold) for maltoheptaoside. Collectively, these results suggest that W641 and the chain of water molecules may be critical for the alpha-amylase activity.
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(as it appears on PubMed at http://www.pubmed.gov), where 14678792 is the PubMed ID number.
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{{ABSTRACT_PUBMED_14678792}}
==About this Structure==
==About this Structure==
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[[Category: Mutagenesis]]
[[Category: Mutagenesis]]
[[Category: Tri]]
[[Category: Tri]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:51:39 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 14:30:37 2008''

Revision as of 11:30, 28 July 2008

Image:1q4n.png

Template:STRUCTURE 1q4n

Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity

Template:ABSTRACT PUBMED 14678792

About this Structure

1Q4N is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Structural studies of a Phe256Trp mutant of human salivary alpha-amylase: implications for the role of a conserved water molecule in enzyme activity., Ramasubbu N, Sundar K, Ragunath C, Rafi MM, Arch Biochem Biophys. 2004 Jan 1;421(1):115-24. PMID:14678792

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