DESIGN OF A NEW PROTEASE INHIBITOR BY THE MANIPULATION OF THE BAIT REGION OF ALPHA(2)-MACROGLOBULIN - INHIBITION OF THE TOBACCO ETCH VIRUS PROTEASE BY MUTANT ALPHA(2)-MACROGLOBULIN

Human alpha(2)-macroglobulin (alpha(2)M) inhibits a broad spectrum of proteases by changing its conformation and physically confining the enzyme. The inhibitory spectrum of alpha(2)M is defined by a stretch of 39 amino acids, the bait region, located near the middle of the alpha(2)M monomers. To investigate whether a new inhibitory specificity can be introduced by the manipulation of the bait region, recombinant alpha(2)M (r alpha(2)M) was produced in which the primary cleavage site was replaced by a heptapeptide containing the cleavage specificity of tobacco etch virus (TEV) protease. This protease is not inhibited by wild-type alpha(2)M. The r alpha(2)M, produced in an episomal expression system, was fully functional and able to inhibit the tobacco etch virus protease according to its normal 'trap' mechanism. The manipulation of the bait region of alpha(2)M thus allows the design of new, specific protease inhibitors.