Design and Synthesis of 'Chymohelizyme-1', a Peptide Having Chymotrypsin-LikeCatalytic Activity

摘要

Enzymes having improved properties have been sought by: site-directed mutagenesisof existing enzymes; design of catalytic antibodies; and design of de novo molecules having enzyme-like properties. Using the third approach, we have designed and synthesized a 73-residue peptide having esterase and amidase properties resembling those of chymotrypsin (CT). A preliminary account of this work has appeared. Several investigations have reported synthesis of peptides designed to adopt specific secondary and tertiary structures, but they have not reported incorporation of enzyme active site residues into these structures. The 3-dimensional structure of CT from the Brookhaven X-ray data base was loaded into a Silicon Graphics IRIS computer, using Tripos MENDYL software. The active site Ser, His and Asp residues were retained, and the rest of the protein was discarded. A bundle of four amphipathic alpha helical peptides was designed to hold these residues in the proper 3-D space and to provide a substrate-binding site for acetyltyrosine ethyl ester (ATEE), a classical CT substrate.