Purification and characterization of chymodenin. A hormone-like peptide from porcine duodenum

Chymodenin, a hormone-like duodenal peptide which rapidly alters the proportions of secreted pancreatic digestive enzymes to a mixture relatively richer in chymotrypsinogen than that found in basal secretion, has been purified to homogeneity. The starting material was an acidic methanol-soluble, neutral pH-insoluble fraction of an acetic acid extract of porcine duodenum; the purification consisted of cation-exchange chromatography on SP-Sephadex and CM-Sephadex in ammonium bicarbonate gradients, and gel filtration on Sephadex G-75 in dilute acetic acid. The yield of material was followed by radioimmunoassay. Homogeneity was determined from chymodenin's behavior in disc gel electrophoresis in an acidic counter-migration-of-dye system, sodium dodecyl sulfate-urea gels, gel filtration, dansyl-Edman reaction, reversed-phase high pressure liquid chromatography, isotachophoresis, and sedimentation equilibrium ultracentrifugation. The electrophoretic mobility, the molecular weight of 9,000-10,000, and the biological activity differed from those of other gastrointestinal peptide hormones. The amino acid composition was unique. Chymodenin is the first purified hormone-like substance reported capable of altering the composition of the mixture of secreted digestive enzymes, independent of the stimulation of massive pancreatic protein output.