Measurement and Study of Substrate Specificity of Exoglucosidase Activity in Eutrophic Water

Abstract

The α- and β-glucosidase activity in natural samples can be readily measured during short incubation times (20 min) by using the artificial substrates 4-methylumbelliferyl-α- d -glucoside and 4-methylumbelliferyl-β- d -glucoside. The apparent K m of both α- and β-glucosidase for these respective substrates is 0.01 μM. The homologous disaccharides maltose and cellobiose competitively inhibit α- and β-glucosidase, respectively. Absolute substrate specificity of the α- and β-glucosidase is observed with respect to the configuration of carbon atoms 1 and 4. Enrichment cultures on either α- and β-glucoside result in increasing activity of the corresponding glucosidase, both in absolute terms and with respect to the other glucosidase.