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1smd
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(New page: 200px<br /> <applet load="1smd" size="450" color="white" frame="true" align="right" spinBox="true" caption="1smd, resolution 1.6Å" /> '''HUMAN SALIVARY AMYLA...)
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Revision as of 17:09, 12 November 2007
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HUMAN SALIVARY AMYLASE
Overview
Salivary alpha-amylase, a major component of human saliva, plays a role in, the initial digestion of starch and may be involved in the colonization of, bacteria involved in early dental plaque formation. The three-dimensional, atomic structure of salivary amylase has been determined to understand the, structure-function relationships of this enzyme. This structure was, refined to an R value of 18.4% with 496 amino-acid residues, one calcium, ion, one chloride ion and 170 water molecules. Salivary amylase folds into, a multidomain structure consisting of three domains, A, B and C. Domain A, has a (beta/alpha)(8-) barrel structure, domain B has no definite topology, and domain C has a Greek-key barrel structure. The Ca(2+) ion is bound to, Asnl00, Arg158, Asp167, His201 and three water molecules. The Cl(-) ion is, bound to Arg195, Asn298 and Arg337 and one water molecule. The highly, mobile glycine-rich loop 304-310 may act as a gateway for substrate, binding and be involved in a 'trap-release' mechanism in the hydrolysis of, substrates. Strategic placement of calcium and chloride ions, as well as, histidine and tryptophan residues may play a role in differentiating, between the glycone and aglycone ends of the polysaccharide substrates., Salivary amylase also possesses a suitable site for binding to enamel, surfaces and provides potential sites for the binding of bacterial, adhesins.
About this Structure
1SMD is a Single protein structure of sequence from Homo sapiens with CA and CL as ligands. The following page contains interesting information on the relation of 1SMD with [Alpha-amylase]. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.
Reference
Structure of human salivary alpha-amylase at 1.6 A resolution: implications for its role in the oral cavity., Ramasubbu N, Paloth V, Luo Y, Brayer GD, Levine MJ, Acta Crystallogr D Biol Crystallogr. 1996 May 1;52(Pt 3):435-46. PMID:15299664
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