title: Binding of Starch Fragments to the Starch Branching Enzyme: Implications for Developing Slower-Digesting Starch.
abstract: Molecular weight distributions of starch branches affect functional properties, which can be controlled by engineering starch branching enzymes (SBEs). Molecular dynamics and docking approaches are used to examine interactions between SBE and starch fragments. In the native protein, three residues formed stable interactions with starch fragments in the central binding region; these residues may play key roles in substrate recognition. Fragments containing 5-12 glucose units interacted more tightly with SBE than smaller fragments, suggesting a minimal functional fragment size of 5, agreeing with experiment. Effects of three different point mutations on interactions with maltopentaose in the central binding region correlated well with experiment. Simulations indicate that SBE may template formation of the crystalline lamellae characteristic of native starch, consistent with the observation that crystalline lamellae formed by starch in a plant, are not necessarily the state of lowest free energy. The methodology will help develop starches with optimized functional properties.
authors.affiliation: †Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, China, 430030.
authors.forename: Rob Marc
authors.initials: RM
authors.lastname: Go
authors.forename: Alan E
authors.initials: AE
authors.lastname: Mark
authors.forename: Alpeshkumar K
authors.initials: AK
authors.lastname: Malde
authors.affiliation: †Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan, China, 430030.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Gilbert
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000737:chemistry*; D000595:Amino Acid Sequence; D004063:Digestion / Q000502:physiology*; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D008970:Molecular Weight; D010944:Plants / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*
chemical_list: D013213:Starch; D015061:1,4-alpha-Glucan Branching Enzyme