Abstract

Many genetic variants of [alpha]_1-antitrypsin have been associated with early onset emphysema and liver cirrhosis. However, the detailed structural basis of pathogenic [alpha]_1-antitrypsin molecules is rarely known. Here we found that a recombinant M_malton variant (Phe52-deleted) lost inhibitory activity by spontaneous conformational conversion into a more stable, inactive form under physiological conditions. Biochemical and spectroscopic data suggested that the variant converts into a reactive center loop-inserted conformation, resembling the latent form of plasminogen activator inhibitor-1.

• Keywords: antitrypsin; conformational change; latent form; serine protease inhibitors