The N-terminal region of NS3 serine proteinase of hepatitis C virus is important to maintain its enzymatic integrity.

Nepatitis C virus codes a serine proteinase in non-structural protein 3 (NS3) to produce viral replicative machinery. Recently, we reported that the activity of NS3 proteinase (region 1058-1214) was efficiently inhibited by some chelators, Kinetic analysis revealed that its Km value was 3.9mM. In contrast, an enzyme covering region 1027-1214 (including N-ternninal region of NS3) was found to show an improved Km of 0.3mM a and a remarkably reduced susceptibility to EDTA. These results suggest that the N-terminal region of NS3 is not essential for the proteinase activity but indispensable to maintain its structural integrity. (C) 1997 Academic Press.