Soluble chromogenic substrates for the assay of endo-1,4-β-xylanases and endo-1,4-β-glucanases

New soluble chromogenic substrates were prepared for specific and rapid assays of endo-1,4-beta-xylanases and endo-1,4-beta-glucanases. A soluble beechwood 4-O-methyl-D-glucurono-D-xylan was dyed with Remazol brilliant blue R, and hydroxyethylcellulose was coupled to Ostazin brilliant red H-3B. The assays are based on photometric measurements of the enzyme-released dyed fragments soluble in the presence of organic solvents which precipitate the original substrates and their high-molecular-weight fractions. The assays are advantageous for rapid analyses of large amount of samples and also permit evaluation of the activities of both enzymes in the presence of exo-beta-glycanases and beta-glycosidases, at a high level of reducing compounds and viable cells, on the cell surface and on cell membranes and organelles.