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1q4n

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[[Image:1q4n.gif|left|200px]]<br /><applet load="1q4n" size="350" color="white" frame="true" align="right" spinBox="true"
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[[Image:1q4n.gif|left|200px]]
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caption="1q4n, resolution 2.07&Aring;" />
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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'''<br />
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{{Structure
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|PDB= 1q4n |SIZE=350|CAPTION= <scene name='initialview01'>1q4n</scene>, resolution 2.07&Aring;
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|SITE=
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|LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene> and <scene name='pdbligand=TAM:TRIS(HYDROXYETHYL)AMINOMETHANE'>TAM</scene>
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|ACTIVITY= [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]
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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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'''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==
==Overview==
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==About this Structure==
==About this Structure==
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1Q4N is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=CA:'>CA</scene>, <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=TAM:'>TAM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q4N OCA].
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1Q4N is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q4N OCA].
==Reference==
==Reference==
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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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14678792 14678792]
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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:[http://www.ncbi.nlm.nih.gov/pubmed/14678792 14678792]
[[Category: Alpha-amylase]]
[[Category: Alpha-amylase]]
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: inhibitor]]
[[Category: inhibitor]]
[[Category: mutagenesis]]
[[Category: mutagenesis]]
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[[Category: tris]]
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[[Category: tri]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:35:50 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 13:32:53 2008''

Revision as of 11:32, 20 March 2008

Image:1q4n.gif


PDB ID 1q4n

Drag the structure with the mouse to rotate
, resolution 2.07Å
Ligands: , and
Gene: AMY1A OR AMY1 (Homo sapiens)
Activity: Alpha-amylase, with EC number 3.2.1.1
Coordinates: save as pdb, mmCIF, xml



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 Thu Mar 20 13:32:53 2008

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