1q4n

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[[Image:1q4n.gif|left|200px]]
[[Image:1q4n.gif|left|200px]]
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{{Structure
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<!--
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|PDB= 1q4n |SIZE=350|CAPTION= <scene name='initialview01'>1q4n</scene>, resolution 2.07&Aring;
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The line below this paragraph, containing "STRUCTURE_1q4n", creates the "Structure Box" on the page.
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|SITE=
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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|LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</scene>, <scene name='pdbligand=TAM:TRIS(HYDROXYETHYL)AMINOMETHANE'>TAM</scene>
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] </span>
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or leave the SCENE parameter empty for the default display.
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|GENE= AMY1A OR AMY1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens])
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-->
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|DOMAIN=
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{{STRUCTURE_1q4n| PDB=1q4n | SCENE= }}
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|RELATEDENTRY=
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1q4n FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1q4n OCA], [http://www.ebi.ac.uk/pdbsum/1q4n PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1q4n RCSB]</span>
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}}
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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'''
'''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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[[Category: Single protein]]
[[Category: Single protein]]
[[Category: Ramasubbu, N.]]
[[Category: Ramasubbu, N.]]
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[[Category: amylase]]
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[[Category: Amylase]]
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[[Category: inhibitor]]
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[[Category: Inhibitor]]
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[[Category: mutagenesis]]
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[[Category: Mutagenesis]]
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[[Category: tri]]
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[[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 Sun Mar 30 23:08:42 2008''
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Revision as of 02:51, 3 May 2008

Image:1q4n.gif

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


Overview

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.

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 Page seeded by OCA on Sat May 3 05:51:39 2008

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