The action of a hydrolytic enzyme system from Helianthus tuberosus L. on carbohydrates present in the tubers

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Abstract
Aqueous extracts of tubers of the Jerusalem artichoke (H. tuberosus) show, on incubation, an increase in reducing substances and a decrease in optical rotation. The enzyme or enzymes responsible were freed from the tuber carbohydrates and coned. 20-fold by fractional precipitation with ammonium sulfate. By the use of paper partition chromatography such prepns. were shown to liberate fructose from various substrates, including sucrose, inulin, a levan, and irisin "B"; glucose was detected among the hydrolysis products of inulin. The liberation of reducing sugars from the tuber carbohydrates and from inulin virtually ceased before complete hydrolysis had taken place. The residual combined sugar was in the form of a disaccharide, probably sucrose. From these observations the main hydrolytic activity of tuber prepns. is characterized as that of a fructofuranosidase, with a moderate degree of specificity for such residues linked to position I of another fructose residue.