Studies on peptides. CXLVIII Application of a new deprotecting procedure with trimethylsilyl trifluoromethanesulfonate for the syntheses of two porcine spinal cord peptides, neuromedin U-8 and neuromedin U-25.

Abstract

The usefulness of a new deprotecting procedure was demonstrated in the solution syntheses of two porcine spinal cord peptides, designated neuromedin U-8 and neuromedin U-25. Protected neuromedin U-8 (8-residue peptide), prepared by condensation of two fragments, served as a C-terminal amino component for the synthesis of neuromedin U-25 (25-residue peptide). Onto this fragment, five peptide fragments were successively condensed by the azide procedure to construct the entire amino acid sequence of neuromedin U-25, a possible biosynthetic precursor of neuromedin U-8. All protecting groups were cleaved from protected neuromedin U-8 and neuromedin U-25 by 1 M trimethylsilyl trifluoromethanesulfonate-thioanisole in trifluoroacetic acid. The results were compared with those obtained by trifluoromethanesulfonic acid deprotection. In terms of contractile activity in rat uterus, neuromedin U-25 was twice as active as neuromedin U-8.