Mould ‘glucosaccharase’: a fructosidase

Abstract

The inhibition by free sugars and alcohols of sucrose breakdown by extracts of Penicillium spinulosum was studied by paper chromatography. The rate of formation of oligosaccharides (transfructosidation) from sucrose was decreased by addition of glucose or fructose, in the presence of which a reducing fructose disaccharide was formed. In the presence of various alcohols the breakdown of sucrose was accompanied by the appearance of substances presumed to be the corresponding alkyl-beta-fructofuranosides. No evidence could be obtained for the participation of inorganic phosphate in the action of the fructosidase. The action of extracts of P. spinulosum and other molds on raffinose and stachyose could be explained by the presence of melibiase and of a fructosidase possessing transfructosidase activity. The mold extracts examined hydrolysed melezitose completely, but fractionation by adsorption on aluminium hydroxide, or by filter-paper electrophoresis, yielded prepns. inactive towards melezitose, but still possessing the characteristic transfructosidase activity towards sucrose. All prepns. capable of attacking melezitose could also attack furanose. None of the observations made requires the postulation of an alpha-glucosidase capable of attacking sucrose or sucrose derivatives. It is therefore suggested that the concept of a "gluco-saccharase" (Kuhn, 1923) be abandoned until positive evidence for the existence of the enzyme is obtained.