Family

Glycoside hydrolase, family 14B, plant (IPR001371)

Short name: Glyco_hydro_14B_pln

Overlapping homologous superfamilies

Family relationships

Description

O-Glycosyl hydrolases (EC:3.2.1.) are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [PMID: 7624375, PMID: 8535779]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site.

Family 14 (EC:3.2.1.2, GH14) encompasses the beta-amylase enzymes. Beta-amylases, which are found in plants and bacteria, hydrolyse 1,4-alpha-glucosidic linkages in starch-type polysaccharide substrates, removing successive maltose units from the non-reducing ends of the chains. In Solanum tuberosum (potato), the enzyme has been found to work optimally at 40 degrees C, becoming unstable above this temperature. On the basis of sequence comparisons, plant and bacterial beta-amylases can be readily distinguished from each other.

The 3D structure of a complex of soybean beta-amylase with an inhibitor (alpha-cyclodextrin) has been determined to 3.0A resolution by X-ray diffraction [PMID: 1491009]. The enzyme folds into large and small domains: the large domain has a (beta alpha)8 super-secondary structural core, while the smaller is formed from two long loops extending from the beta-3 and beta-4 strands of the (beta alpha)8 fold [PMID: 1491009]. The interface of the two domains, together with shorter loops from the (beta alpha)8 core, form a deep cleft, in which the inhibitor binds [PMID: 1491009]. Two maltose molecules also bind in the cleft, one sharing a binding site with alpha-cyclodextrin, and the other sitting more deeply in the cleft [PMID: 1491009].

GO terms

Biological Process

GO:0000272 polysaccharide catabolic process

Molecular Function

GO:0016161 beta-amylase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PRINTS