In Situ Extension as an Approach for Identifying Novel -Amylase Inhibitors*

A new approach for the discovery and subsequent structural elucidation of oligosaccharide-based inhibitors of -amylases based upon autoglucosylation of known -glucosidase inhibitors is presented. This concept, highly analogous to what is hypothesized to occur with acarbose, is demonstrated with the known -glucosidase inhibitor, D-gluconohydroximino-1,5-lactam. This was transformed from an inhibitor of human pancreatic -amylase with a Ki value of 18 mM to a trisaccharide analogue with a Ki value of 25 M. The three-dimensional structure of this complex was determined by x-ray crystallography and represents the first such structure determined with this class of inhibitors in any -glycosidase. This approach to the discovery and structural analysis of amylase inhibitors should be generally applicable to other endoglucosidases and readily adaptable to a high throughput format.