Binding interactions between barley thaumatin‐like proteins and (1,3)‐β‐D‐glucans

摘要: The specificity and kinetics of the interaction between the pathogenesis-related group thaumatin-like proteins (PR5) in higher plants (1,3)-β-d-glucans have been investigated. Two with 60% amino-acid sequence identity were purified from extracts germinated barley grain, designated HvPR5b and HvPR5c. Purified HvPR5c interacted insoluble (1,3)-β-d-glucans, but not cellulose, pustulan, xylan, chitin or a yeast mannoprotein. Tight binding was observed unbranched unsubstituted weaker seen if (1,6)-β-linked branch points β-glucosyl substituents present substrate. protein weakly did bind to any other polysaccharides tested. This indicated that only specific PR5 isoforms interact tightly (1,3)-β-d-glucans. complete primary structures determined used construct molecular models HvPR5c, based on known three-dimensional related proteins. examined for features may be associated (1,3)-β-d-glucan binding, potential (1,3)-β-d-glucan-binding region located surface HvPR5c. No obvious structural would prevent identified, several amino acids are likely HvPR5b.