The Enzymic Hydrolysis of p - Glucosides

The present work arose out of an attempt to understand the course of cellulose breakdown in preparations of cellulolytic enzymes which also contained cellobiase activity. Previous investigations of the ,B-glucosidases have been of three kinds-an examination of their specificity ranges (reviewed by Veibel, 1950), the demonstration of their reversibility and the study of glucosyl transfer. Croft-Hill (1898), in demonstrating the reversibility ofenzyme reactions, showed the formation of disaccharides from glucose in the presence of yeast enzymes. Gentiobiose was later found to be the chief product of this type of reaction catalysed by fl-glucosidases (Bourquelot & Bridel, 1919; Bourquelot, Herissey & Coirre, 1913), and it is now a recognized method of preparing this sugar (Helferich & Leete, 1942). More recently, Peat, Whelan & Hinson (1952) have shown that five #-linked glucose disaccharides can be obtained by incubating 60% glucose with almond emulsin over a period of 5 weeks. Aliphatic and aromatic alcohols, too, can condense with glucose in the presence of P-glucosidases (Bourquelot & Bridel, 1913; Veibel, 1936; Vintilescu, Ionescu & Kizyk, 1934, 1935a, b; Vintilescu, Ionescu & Solomon, 1935). The first to describe transglycosylation and to realize the complementary role of the reactants was Rabate (1935), who showed that methyl P-glucoside was formed when piceoside (p-hydroxyacetophenone fl-glucoside) was incubated with methanol and extracts of Salix purpurea, and that glucosidically linked glucose was necessary for the reaction. Miwa, Takano, Mafune & Furutani (1949), Miwa & Takano (1950), Takano & Miwa (1950) and Jermyn & Thomas (1953) confirmed these results and extended them, using a series of fungal and plant extracts acting upon several aromatic fl-glucosides in the presence of methanol, ethanol or butanol. In 1953 Crook & Stone reported the formation of a series of oligosaccharides from cellobiose in the presence of various enzyme preparations. Since then Barker, Bourne & Stacey (1953), Barker, Bourne, Hewitt & Stacey (1955), Buston & Jabbar (1954), Giri, Nigam & Srinivasan (1954) and Kooiman, Roelofsen & Sweeris (1954) have described similar reactions with various mould enzyme preparations. Manners (1955) has observed the formation of higher saccharides during the