I. Characteristics of the ßbeta;-glucosidase activity of intact and of lysed cells

J. Gordin Kaplan ¹

¹ From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.

Until September 1, 1965, Dr. Kaplan's address will be Laboratoire de Génétique Physiologique du Centre National de la Recherche Scientifique, Gif-Sur-Yvette (Seine et Oise), France

A strain of bakers' yeast was isolated which could utilize cellobiose and other ß-D-glucosides quantitatively as carbon and energy sources for growth. Cellobiose-grown cells contained a largely cryptic enzyme active against the chromogenic substrate p-nitrophenyl-ß-D-glucoside. The patent (intact cell) activity of such cells was inhibited by azide and, competitively, by cellobiose; neither agent inhibited the ß-glucosidase activity of lysed cells or of extracts. The enzyme induced by growth in cellobiose medium had no affinity for cellobiose as either substrate or inhibitor; its substrate specificity classifies it as an aryl-ß-glucosidase. It was concluded that growth in cellobiose also induced the formation of a stereospecific and energy-dependent system whose function determined the rate at which intact cells could hydrolyze substrates of the intracellular ß-glucosidase.

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