title: Chemical genetics and cereal starch metabolism: structural basis of the non-covalent and covalent inhibition of barley β-amylase.
abstract: There are major issues regarding the proposed pathway for starch degradation in germinating cereal grain. Given the commercial importance but genetic intractability of the problem, we have embarked on a program of chemical genetics studies to identify and dissect the pathway and regulation of starch degradation in germinating barley grains. As a precursor to in vivo studies, here we report systematic analysis of the reversible and irreversible inhibition of the major β-amylase of the grain endosperm (BMY1). The molecular basis of inhibitor action was defined through high resolution X-ray crystallography studies of unliganded barley β-amylase, as well as its complexes with glycone site binder disaccharide iminosugar G1M, irreversible inhibitors α-epoxypropyl and α-epoxybutyl glucosides, which target the enzyme's catalytic residues, and the aglycone site binders acarbose and α-cyclodextrin.
authors.affiliation: Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Rejzek
authors.forename: Clare E
authors.initials: CE
authors.lastname: Stevenson
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Southard
authors.forename: Duncan
authors.initials: D
authors.lastname: Stanley
authors.forename: Kay
authors.initials: K
authors.lastname: Denyer
authors.forename: Alison M
authors.initials: AM
authors.lastname: Smith
authors.forename: Mike J
authors.initials: MJ
authors.lastname: Naldrett
authors.forename: David M
authors.initials: DM
authors.lastname: Lawson
authors.forename: Robert A
authors.initials: RA
authors.lastname: Field
mesh_terms: D018360:Crystallography, X-Ray; D002523:Edible Grain / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D056625:Endosperm / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008958:Models, Molecular; D008968:Molecular Conformation; D013213:Starch / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D001614:beta-Amylase / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D013213:Starch; D001614:beta-Amylase