Monkey Pepsinogens and Pepsins

Abstract

Purified Japanese monkey pepsinogens I and II contain carbohydrate as a part of the enzyme molecule. By gel filtration on Sephadex G-100, chromatography on DE-32 cellulose, and polyacrylamide disc gel electrophoresis, the carbohydrate moiety could not be separated from the enzyme protein, and the content did not decrease on repeated chromatography. Glycopep-tides were obtained by successive digestion of pepsinogens with thermolysin and amino-peptidases and isolated by chromatography on Sephadex G-25 and G-50. Identification and determination of carbohydrate components was performed by paper and gas-liquid chro-matographies. The presence of 4 glucosamines, 6 galactoses, 6–8 mannoses, and 8–11 .fucoses per molecule of the glycopeptide of both pepsinogens was observed, of which the high content of fucose is especially unique. The molecular weight of the carbohydrate chains should be around 4,000–5,000. The amino acid sequence of a major glycopeptide was deduced to be Ile-Gly-Ile-Gly-Thr-Pro-Gln-Ala-Asn, in which the asparagine residue is the site of attachment of the carbohydrate chain.