AN IMPROVED SOLID-PHASE METHOD FOR PEPTIDE SYNTHESIS—THE SYNTHESES OF OXYTOCIN AND VASOPRESSIN

Peptide hormones are now widely used for both medicinal and veterinary purposes.It is, therefore, imminent to improve the process of peptide synthesis to meet the needsof production. This paper describes an improved method for the solid-phase synthesis ofpeptides. By reacting the potassium salt, instead of the triethyl ammonium salt, of theN-protected amino acid with the chloromethylated polystyrene-divinyl benzene (2%) sup-port, esterification was found to attain higher levels, thus obviating or minimizing theformation of a quaternary anion exchanger which might cause side reactions during thesubsequent steps of synthesis. The method has been applied to the syntheses of oxytocinand vasopressin and found to be quite satisfactory. A new method was introduced forthe determination of free α-amino groups of the peptide polymer support through the for-mation of a Schiff’s base with salicylaldehyde.