Potent human alpha;-amylase inhibition by the β-defensin-like protein helianthamide

Abstract

Selective inhibitors of human pancreatic α-amylase (HPA) are an effective means of controlling blood sugar levels in the management of diabetes. A high-throughput screen of marine natural product extracts led to the identification of a potent (Ki = 10 pM) peptidic HPA inhibitor, helianthamide, from the Caribbean sea anemone Stichodactyla helianthus. Active helianthamide was produced in Escherichia coli via secretion as a barnase fusion protein. X-ray crystallographic analysis of the complex of helianthamide with porcine pancreatic α-amylase revealed that helianthamide adopts a β;-defensin fold and binds into and across the amylase active site, utilizing a contiguous YIYH inhibitory motif. He..