Starch branching enzymes contributing to amylose and amylopectin fine structure in wheat. (15th November 2019)

• Record Type: Journal Article
• Authors: Li, Haiteng; Yu, Wenwen; Dhital, Sushil; Gidley, Michael J.; Gilbert, Robert G.
• Is Part Of: Carbohydrate polymers. Volume 224(2019)
• Publication Date: 2019-11-15
• Subjects: CLD chain length distribution -- DP degree of polymerization -- SS starch synthase -- SBE starch branching enzyme -- DBE starch debranching enzyme -- RS resistant starch -- SEC size-exclusion chromatography -- AM amylose content; High amylose starch -- Starch structure -- Branching enzyme -- Wheat -- Chain-length distribution; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2019.115185
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Fitting CLDs to amylose and amylopectin models reveals SBE II functions in wheat. SBE IIa acts on relatively short branches in amylopectin. SBE IIb acts on relatively long branches in amylopectin. SBE IIa acts on longer amylose chains with ˜3000 monomer units. The effect of SBE IIb on amylose fine structure is not significant. Abstract: Starch branching enzymes (SBEs) play a major role in determining starch molecular structure in cereal endosperm. This study investigates how SBEIIs contribute to the chain-length distributions (CLDs) of both amylopectin and amylose, obtained by enzymatic debranching of native starch. Wheat starches with low (37%) to high (93%) amylose content were obtained through altering SBEII in planta. Multiple components were detected in both amylose and amylopectin CLDs. Model fitting of these CLDs reveals a quantitative association between the enzyme activities in amylopectin and amylose. SBEIIa modifies shorter branches (degree of polymerization DP ≲ 12) in amylopectin and longer amylose chains with a CLD peak at ˜3000 DP. SBEIIb acts on longer branches (DP≲ 32) in amylopectin, while its effect on amylose fine structure is not significant. Using both the amylose and amylopectin models to analyze the CLD reveals connections between amylose and amylopectin in wheat starch biosynthesis.