title: Study of the structure and properties of native and hydrothermally processed wild-type, lam and r variant pea starches that affect amylolysis of these starches.
abstract: Starches from WT, lam, and r pea mutants differing in amylopectin/amylose contents (70, 90, and 28% amylopectin, respectively) were used in kinetic studies of pancreatic α-amylase action at 37 °C and for investigations of their supramolecular structure and physicochemical properties during heating. For WT and lam starches, amylase accessibility and catalytic efficiencies (CE) increased following hydrothermal processing up to 100 °C. Accessibility changed relatively less in r during heating with increasing K(m) between 60-90 °C. Limiting values of K(m) after gelatinization were very similar for all three mutants, indicating that relative proportions of amylose/amylopectin have little influence on amylase accessibility once ordered structures are lost. For WT and lam, increases in enzyme accessibility and CE paralleled a rise in amorphous content. It is suggested that the complex behavior for r resulted from amylose gel formation between 60-90 °C. Amorphous amylopectin seems a better substrate for amylase than amorphous amylose.
authors.affiliation: Department of Biochemistry, Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: Rumana
authors.initials: R
authors.lastname: Tahir
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ellis
authors.forename: Tatiana Y
authors.initials: TY
authors.lastname: Bogracheva
authors.forename: Cheryl
authors.initials: C
authors.lastname: Meares-Taylor
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Butterworth
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000235:genetics; D000687:Amylopectin / Q000737:chemistry; D000688:Amylose / Q000737:chemistry; D000818:Animals; D002384:Catalysis; D006358:Hot Temperature; D009154:Mutation; D055292:Pancreatic alpha-Amylases / Q000737:chemistry*; D018532:Pisum sativum / Q000737:chemistry* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D013213:Starch / Q000737:chemistry* / Q000235:genetics; D013552:Swine
chemical_list: D010940:Plant Proteins; D013213:Starch; D000688:Amylose; D000687:Amylopectin; D015061:1,4-alpha-Glucan Branching Enzyme; D055292:Pancreatic alpha-Amylases