PMID: 21085740

Authors:

Rejzek M, Stevenson CE, Southard AM, Stanley D, Denyer K, Smith AM, Naldrett MJ, Lawson DM, Field RA

Title:

Chemical genetics and cereal starch metabolism: structural basis of the non-covalent and covalent inhibition of barley beta-amylase.

Journal:

Mol Biosyst. 2010 Nov 18.

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 beta-amylase of the grain endosperm (BMY1). The molecular basis of inhibitor action was defined through high resolution X-ray crystallography studies of unliganded barley beta-amylase, as well as its complexes with glycone site binder disaccharide iminosugar G1M, irreversible inhibitors alpha-epoxypropyl and alpha-epoxybutyl glucosides, which target the enzyme's catalytic residues, and the aglycone site binders acarbose and alpha-cyclodextrin.