johnson-specificityofbinding-1996.pdf (537.29 kB)
Specificity of binding of β-glucoside activators of ryegrass (1->3)-β-glucan synthase and the synthesis of some potential photoaffinity activators
journal contribution
posted on 1996-08-01, 00:00 authored by K Ng, Liz JohnsonLiz Johnson, B A StoneStructure-activity relationships among glycoside activators of ryegrass (Lolium multiflorum) (1-->3)-beta-glucan synthase were investigated using a number of natural and synthetic glycosides, including some carrying photoaffinity functions. There is an absolute requirement for a beta-D-glycosyl moiety in the activator, both S- and N-glucosides are active, and the position of the glucosidic linkage in beta-glucose disaccharides has a significant effect on the affinity of binding. However, the binding requirement does not extend beyond a single beta-D-glucosyl residue, and beta-D-oligoglucosides are less effective than disaccharides. The nature of the aglycon has a major influence on the binding affinity. Hydrophobic aglycons lower the concentration required for half-maximal stimulation of the enzyme obtained from an Eadie-Hofstee plot of kinetic data (Ka) for activation, but charge aglycons increase Ka. Relative to methyl-beta-D-glucoside and cellobiose (Ka 1.1 mM), the most potent compounds tested were N-[4-(benzoyl)benzoyl]-beta-D-glucosylamine and 2'-[4-azidosalicylamino]ethyl-1-thio-beta-D-glucoside with K(a)s of approximately 30 microM. The latter also was tested for its potential to specifically label the beta-glucoside-binding site on the synthase, but under the conditions used the binding was found to be nonspecific.
History
Journal
Plant physiologyVolume
111Issue
4Pagination
1227 - 1231Publisher
American Society of Plant BiologistsLocation
Rockville, Md.Publisher DOI
Link to full text
ISSN
0032-0889Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
1996, American Society of Plant BiologistsUsage metrics
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