Design and synthesis of a conformationally restricted cysteine protease inhibitor

Molecular graphics analyses use the x-ray data of papain and papain-chloromethyl ketone inhibitor complexes as model cysteine protease to construct a conformationally restricted cysteine protease inhibitor. Two synthetic methods enable the preparation of this inhibitor and it functions as an efficient competitive inhibitor of papain with a K(I) of 790 nM.