Studies on the detergent inhibition of pancreatic lipase activity

Abstract

Pancreatic lipase requires colipase, a protein cofactor, to counteract the in vitro inhibition by bile salt. Lipase activity is inhibited by nonsteroidic detergents regardless of their charge and structure. Detergent-inhibited lipase is reactivated by colipase but in all cases activation is limited to a narrow range of detergent concentration. Complementary studies on the bile salt and detergent effect on lipase activity and on interfacial tension at the substrate-water interface show that inhibition is not related to the interfacial surface tension. It is hypothesized that absorption of amphiphilic compounds to the substrate surface modifies the distribution of the enzyme between the lipid surface and the aqueous phase. The activity of detergent-inhibited lipase is fully restored by adding bile salt to the reaction system. Bile salt might play a critical role during in vivo lipolysis by desorbing surface-active substances from the lipid-water interface thus allowing lipase and colipase to interact with substrate.