β-Glucocerebrosidase: Affinity Purification and Characterization of its Active Site with N-Alkyl Derivatives of 1-Deoxynojirimycin
An essential feature of the catalytic site of practically all β-glucosidases is a carboxylate group in close proximity to the glucosyl C-1 of the bound substrate. It participates in the bond breaking step by stabilizing a positive charge developing at this carbon atom and/or by forming an α-glucosyl enzyme intermediate which subsequently hydrolyses to β-glucose. The presence and orientation with respect to the bound substrate of this carboxylate is revealed by the covalent inhibition of these enzymes by epoxides related to glucose and by their strong non-covalent inhibition by glucose derivatives with a basic group at C-1 which is up to 103-times better than by the corresponding non-basic derivativesl. We have used the latter property to develop an affinity purification for β-glucocerebrosidase from calf spleen and to explore the aglycon part of its active site with N-alkyl derivatives of 1-deoxynojirimycin (dNM, 1,5-dideoxy-1,5-imino-D-glucitol), a basic analogue of D-glucose where the pyranose oxygen has been replaced by an NH-group.
KeywordsAffinity Purification Sebacic Acid Basic Analogue Enzyme Intermediate Reductive Alkylation
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