Screening an α-glucosidase inhibitor from a phage-displayed peptide library

A phage-displayed peptide library was biopanned with Aspergillus niger glucoamylase. Three specifically binding phage clones (GB-1, GB-2 and GB-3) were identified after three cycles of screening and amplification All three peptides contained a disulfide bridge, and the impairment of disulfide bond greatly lowered the binding activity. One peptide, cyclic KCHFEECLAY, representing the N-terminal 10 amino acid residues from GB-1, competitively inhibited A. niger glucoamylase (K-i = 0. 2 mmol/L) as well as rat intestinal alpha -glucosidase (K-i = 1. 4 mmol/L).