Biochemical and immunological characterizations of rat pepsinogens and pepsins

Biochemical and immunological properties of two kinds of pepsinogens isolated from the gastric mucosal extracts of adult Wistar rats were studied. Their activated enzymes were prepared from the zymogens using a DEAE-Sepharose CL-6B column. The isoelectric points of pepsinogens I and II were estimated to be 3.90 and 3.75, respectively, by isoelectric focusing, and those of pepsins I and II to be 3.60 and 3.45, respectively. Amino acid compositions of the two pepsinogens or pepsins were strikingly similar to each other and neither pepsinogen I nor II contained organic phosphate. The biochemical properties of rat preparations compared with porcine pepsinogens A and C and pepsins A [EC 3.4.23.1] and C [EC 3.4.23.3] showed that rat pepsinogens and pepsins resembled porcine pepsinogen C and pepsin C, respectively. Pepsinogens I and II were demonstrated to share a similar immunogenic molecular structure by double diffusion analysis and Laurell immunoelectrophoresis. Rabbit antipepsinogen I serum cross-reacted with the mouse preparation but did not with the rabbit and porcine preparations. The possibility of the genetically controlled occurrence of pepsinogens I and II in the rat is discussed.