[Modified proteinases in peptide synthesis in organic media]

We showed that modified proteases could catalyze synthesis of a wide variety of peptides of various lengths and structures both in solution and on solid phase in organic solvents. The following modified proteases were studied as catalysts for enzymatic peptide synthesis in polar organic solvents (acetonitrile, dimethylformamide, and ethanol): pepsin sorbed on celite, a noncovalent complex of subtilisin with sodium dodecylsulfate, and subtilisin or thermolysin covalently immobilized on a cryogel of polyvinyl alcohol. The use of the noncovalent complex of subtilisin with sodium dodecylsulfate and immobilized subtilisin is especially promising for the segment condensation of peptide fragments containing residues of trifunctional amino acids with unprotected ionogenic groups in side chains, such as Lys, Arg, His, Glu, and Asp.