Département de chimie moléculaire

Enzymic modification of saccharidic biomass is a subject of intensive research with potential applications in plant or human health, design of biomaterials and biofuel prodn. Bioengineering and metagenomics provide access to libraries of glycoside hydrolases but the biochem. characterization of these enzymes remains challenging, requiring fastidious colorimetric tests in discontinuous assays. Here, we describe a highly sensitive carbohydrate biosensor for the detection and characterization of glycoside hydrolases. Immobilization of oligosaccharides was achieved using copper-catalyzed azide-alkyne cycloaddn. of maltoheptaose-modified probes onto self-assembled monolayers bearing azide reactive groups. This biosensor allowed detection of glycoside hydrolase activities at the picomolar level using quartz-crystal microbalance with dissipation monitoring (QCM-D). To our knowledge, this protocol provides the best performance to date for the detection of glycoside hydrolase activities. For each enzyme tested, we could det. the kinetic const. from the QCM-D data, and derive conclusions that correlated well with those of std. colorimetric tests. This opens the way to a new generation of rapid and direct tests characterizing functionally carbohydrate-active enzymes. [on SciFinder(R)]