Substrate specificity of rumen cellulolytic enzymes

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Abstract
Specificity studies on cell-free extracts of cellulolytic enzymes from sheep rumen have been extended to cellophan and cellulose dextrin, which have been found to be hydrolyzed at lower rates than carboxymethylcellulose, particularly cellophan. D-Glucono-1 [forward arrow] 4-lactone has been shown to be a specific inhibitor of glucose production from carboxymethylcellulose, cellulose dextrin and also cellosaccharides from cellobiose to cellopentaose, producing at least 80% inhibition at a concentration of 2. 5 mM. Inhibition of hydrolysis of mM cellosaccharides in the series cellobiose-cellopentaose by 2. 5 nM gluconolactone has shown the hydrolysis of cellobiose to be completely (99%) inhibited, the inhibition decreasing with chain length to 82% for cellopentaose. The inhibition measured in terms of reducing sugar is generally less than that in terms of glucose. Chromatographic analysis of carboxymethylcellulose hydrolyzates with cellosaccharides as reference substances suggests that small amounts of cellobiose and possibly higher saccharides accumulate in the presence of gluconolactone; other substances, probably substituted derivatives, complicate the analysis.