1smd | pdb_00001smd
HUMAN SALIVARY AMYLASE
Structural highlights
Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSalivary 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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