FREE-SOLUTION CAPILLARY ELECTROPHORESIS OF TRYPTIC DIGEST FRAGMENTS OF A RECOMBINANT PORCINE PRO-GROWTH HORMONE-RELEASING HORMONE (2-76)OH

The application of free-solution capillary electrophoresis (FSCE) to t he separation of peptide fragments produced by tryptic digestion of a new recombinant porcine pro-growth hormone releasing hormone (2-76)OH (rpGHRH) composed of 75 amino acid residues is presented. It was found that 11 digest peptide fragments of rpGHRH could be separated by FSCE using an uncoated fused silica capillary with 0.1 M phosphate buffer, pH 3.3, used as the separating electrolyte. Individual peptide fragme nts prepared by solid phase synthesis method were spiked into the tryp tic digest mixture to verify structure and fragment assignments of the polypeptide in electrophoresis. Optimal separation conditions were ob tained by studying the effect of pH in the separating electrolyte and applied voltage. An excellent correlation was found for the electropho retic migration time, t(m), of the digest peptides versus q/MW(2/3),wh ere q is the calculated charge, and MW is molecular weight of peptides .