β-Glucosyl and α-Galactosyl Yariv Reagents Bind to Cellulose and Other Glucans

Abstract

Yariv reagent [1,3,5-tris(4-β-d-glucopyranosyloxyphenylazo)-2,4,6-trihydroxybenzene] has been used in the purification/quantification of arabinogalactan-proteins and as a histochemical reagent to localize arabinogalactan-proteins in plant tissues. When developing cotton fiber cells were stained with β-glucosyl Yariv reagent, interference from other cell wall polymers, especially cellulose, was suspected. In order to examine this potential interference, we have developed two dye-binding assays to measure the binding of Yariv reagent in the presence of various carbohydrate polymers. Reaction conditions such as pH, ionic strength, and exposure time in the standard binding assays were investigated. The results show that β-glucosyl and α-galactosyl Yariv reagents bind to cellulose and several other glucans. Treatments with excess glucose in the assay to inhibit binding were only partially effective in preventing β-glucosyl Yariv reagent from binding to cellulose. Keywords: Arabinogalactan protein; cellulose; glucan; histochemical stain; Yariv reagent