Domain characterization of a 4-alpha-glucanotransferase essential for maltose metabolism in photosynthetic leaves.

ABSTRACT: Maltose metabolism during the conversion of transitory (leaf) starch to sucrose requires a 4-alpha-glucanotransferase (EC 2.4.1.25) in the cytosol of leaf cells. This enzyme is called DPE2 because of its similarity to the disproportionating enzyme in plastids (DPE1). DPE1 does not use maltose; it primarily transfers a maltosyl unit from one maltotriose to a second maltotriose to make glucose and maltopentaose. DPE2 is a modular protein consisting of a family 77 glycosyl hydrolase domain, similar to DPE1, but unlike DPE1 the domain is interrupted by an insertion of approximately 150 amino acids as well as an N-terminal extension that consists of two carbohydrate binding modules. Phylogenetic analysis shows that the DPE2-type enzyme is present in a limited but highly diverse group of organis

SUBMITTER: Steichen JM 

PROVIDER: S-EPMC3258926 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature