PMID: 6976347Jan 25, 1982Paper

A unique "mini" pepsinogen isolated from bullfrog esophageal glands.

The Journal of Biological Chemistry
R P ShugermanJ G Spenney

Abstract

The evolutionary homology of pepsinogens was further evaluated by isolating and characterizing the pepsinogen of the esophageal glands of Rana catesbeiana. Like other pepsinogens, this esophageal enzyme was activated by acid; the resulting pepsin was optimally active between pH 1.4 and 2.0, and was irreversibly denatured above pH 7.0. Chromatography on DEAE-cellulose at pH 7.0 separated four acid protease fractions corresponding to pepsinogens B, D, A, and C. Hydroxylapatite chromatography of the major peptic fraction, pepsinogen A, followed by rechromatography on DEAE-cellulose at pH 8.5 yielded pure pepsinogen A which was free of detectable contaminants. Estimation of molecular weight by gel filtration on Sephadex G-75, by polyacrylamide gel electrophoresis in 0.1% SDS and by sedimentation equilibrium gave values of 31,500, 33,500, and 33,700, respectively. These studies suggest that the difference between bullfrog and other pepsinogens is located in a 90 to 110 amino acid (Mr 9,000 to 11,000) region of the molecule which must be remote from the catalytic and immunogenic sites. This lower molecular weight pepsinogen should thus provide a simpler molecular model for study of the catalytic and immunogenic properties. The pepsin...Continue Reading

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