Total synthesis of bovine pancreatic ribonuclease A. Part 6. Synthesis of RNase A with full enzymic activity

Abstract

Protected bovine pancreatic RNase A was synthesized by azide condensation of the three fragments Z(OMe)-(RNase 21–124)-OBzl, Z(OMe)-(RNase 9–20)-NHNH₂, and Z-(RNase 1–8)-NHNH₂. After removal of the protecting groups by methanesulphonic acid, establishment of the disulphide bridges by aerial oxidation, and purification by affinity chromatography and ion-exchange chromatography on CM-cellulose, a synthetic protein was obtained which was indistinguishable by chemical and enzymatic criteria from natural RNase A. Comparable results were also obtained when HF was used as a deprotecting reagent. The unambiguous synthesis of a protein having full enzymic activity has thus been accomplished for the first time.