Semisynthetic studies on bovine pancreatic ribonuclease

The S-peptide of the enzyme bovine pancreatic ribonuclease has been used as a model for covalent semisynthesis. Methods for side-chain protection, enzymatic cleavage of the peptide chain at the level of the single arginine-10 and for selective deprotection of the α-carboxyl function of this residue, have been examined. The partially protected [1–10] sequence has been coupled to a solid-phase generated [11–15] sequence attached to the polymer. After deblocking from the solid-support, the [1–15] semisynthetic peptide was complexed with native S-protein to give a complex with high biological activity.