What is the structure of human salivary alpha-amylase?

The structure of human salivary alpha-amylase is a folded chain of 496 amino acid residues. It also includes one calcium ion and one chloride ion.

The enzymatic active site of alpha-amylase is composed of three acidic groups and a chloride ion. A single calcium ion is needed for structural stability. Alpha-amylase is a member of the hydrolase enzyme family and may be found across multiple species. The enzyme is also present in plants, fungi and bacteria. Human salivary alpha-amylase initiates the degradation of starch into glucose. The enzyme is inactivated in the stomach, where the similarly structured pancreatic amylase continues the digestion process.