Purification and analysis of synthetic, triple-helical "minicollagens" by reversed-phase high-performance liquid chromatography.

Abstract To better study collagen-mediated cellular and enzymatic activities, a generally applicable solid-phase methodology has been developed by which aligned triple-helical peptides (designated THPs or "minicollagens") ranging from 79 to 124 residues can be assembled. Reversed-phase HPLC is typically the purification method of choice following chemical synthesis of small proteins of this size, as well as one of the analytical techniques used to verify product purity. We have thus compared the effects of different stationary phases (C 18 , C 4 , or diphenyl), organic modifiers (acetonitrile or isopropanol), support pore sizes (120 A 300 A or nonporous), and counterions for the reversed-phase HPLC analysis of THPs. Large-pore C 18 or C 4 reversed-phase HPLC gave broad THP peaks, resulting in poor resolution of the desired THP from synthetic impurities. Broad peaks were presumably due to conformational instability of THPs to reversed-phase HPLC conditions and subsequent slow cis-trans isomerization of the peptide bonds. Peak sharpness was improved greatly by using large-pore diphenyl reversed-phase HPLC. We found that THPs can be best resolved from synthetic impurities by diphenyl or nonporous C 18 reversed-phase HPLC using water-acetonitrile gradients. These results most likely reflect conditions which maintain the native conformation of collagen-like triple-helices.