[Sequential attachment of arginine residues to peptides, catalyzed by subtilisin. 1. Effect of organic solvent composition].

Subtilisin 72 sorbed on a macroporous glass catalyzed the condensation of Dnp(or Z)-Ala2-Leu-OCH3 with arginine amide in a mixture of DMSO and acetonitrile at a water content less than 0.07% (v/v). This reaction resulted in the sequential formation of peptides containing from one to four C-terminal arginine residues. The number of attached Arg residues depended on the DMSO concentration in the solvent mixture, which determined the local arginine excess on the sorbent surface, which significantly exceeded the molar arginine excess in the solution. This enzymic reaction opened up new opportunities for preparation of peptides with different content of arginine residues.