Alpha-amylase/branching enzyme, C-terminal all beta

Definition

This entry represents the all-β C-terminal domain that is found in members of the glycosyl hydrolase 13 family, such as alpha-amylases and 1,4-alpha-glucan branching enzyme. This domain forms a Greek key β-barrel fold in these enzymes PMID:7877175. Alpha-amylase is classified as family 13 ([cazy:GH13]) of the glycosyl hydrolases and is present in archaea, bacteria, fungi, plants and animals. Alpha-amylase is an essential enzyme in alpha-glucan metabolism, acting to catalyse the hydrolysis of alpha-1,4-glucosidic bonds of glycogen, starch and related polysaccharides. Although all alpha-amylases possess the same catalytic function, they can vary with respect to sequence. In general, they are composed of three domains: a TIM barrel containing the active site residues and chloride ion-binding site (domain A), a long loop region inserted between the third β-strand and the α-helix of domain A that contains calcium-binding site(s) (domain B), and a C-terminal β-sheet domain that appears to show some variability in sequence and length between amylases (domain C) PMID:11141191. Amylases have at least one conserved calcium-binding site, as calcium is essential for the stability of the enzyme. The chloride-binding functions to activate the enzyme, which acts by a two-step mechanism involving a catalytic nucleophile base (usually an Asp) and a catalytic proton donor (usually a Glu) that are responsible for the formation of the beta-linked glycosyl-enzyme intermediate. Branching enzyme catalyses the formation of alpha-1,6 branch points in either glycogen or starch. It has an important role in the determination of the structure of starch in plants and of glycogen in animals and bacteria PMID:12196524.

6 human proteins with this domain

Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.

Download CSV (6 proteins: gene, accession, name)

• AMY1A
• AMY1B
• AMY1C
• AMY2A
• AMY2B
• GBE1