1SMD

HUMAN SALIVARY AMYLASE

Summary for 1SMD

• Entry DOI: 10.2210/pdb1smd/pdb
• Descriptor: AMYLASE, CALCIUM ION, CHLORIDE ION, ... (4 entities in total)
• Functional Keywords: hydrolase, o-glycosyl, carbohydrate metabolism, hydrolase (o-glycosyl)
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 56030.79

Authors

Ramasubbu, N. (deposition date: 1996-01-24, release date: 1996-07-11, Last modification date: 2024-10-16)

Primary citation

Ramasubbu, N.,Paloth, V.,Luo, Y.,Brayer, G.D.,Levine, M.J.
Structure of human salivary alpha-amylase at 1.6 A resolution: implications for its role in the oral cavity.
Acta Crystallogr.,Sect.D, 52:435-446, 1996

PubMed Abstract: 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.

PubMed: 15299664
DOI: 10.1107/S0907444995014119

Experimental method

X-RAY DIFFRACTION (1.6 Å)