The 3-dimensional structure of the amylase molecule

The human pancreatic amylase molecule consists of 496 amino acid residues.
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Primary structure
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Secondary structure
Cartoon format coloured by structure - α helices pinkish red, other helices purple/dark blue, β sheets gold
Note especially the central barrel-shaped section through which the substrate presumably passes as it is fed into the active site.
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Tertiary structure
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Active site
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The following amino acid residues have been identified (reference below) as contributing to the conversion of glucose polysaccharides (amylose, starch) into disacccharides (maltose). Interestingly, they all have acidic side-chains (aspartic acid and glutamic acid).
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Web references

Subsite mapping of the human pancreatic alpha-amylase active site through structural, kinetic, and mutagenesis techniques. Brayer GD, Sidhu G, Maurus R, Rydberg EH, Braun C, Wang Y, Nguyen NT, Overall CM, Withers SG.