1q4n: Difference between revisions
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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''' | {{Structure | ||
|PDB= 1q4n |SIZE=350|CAPTION= <scene name='initialview01'>1q4n</scene>, resolution 2.07Å | |||
|SITE= | |||
|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> | |||
|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] | |||
|GENE= AMY1A OR AMY1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens]) | |||
}} | |||
'''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== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1Q4N is a [ | 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== | ||
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:// | 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]] | ||
[[Category: | [[Category: tri]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''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
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| 1q4n, resolution 2.07Å | |||||||||||||
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| Ligands: | CA, CL and TAM | ||||||||||||
| 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
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