Guinea pig pancreas ribonucleases. Separation by ion exchange chromatography and the subcellular distribution of these enzymes.

As initial steps in studying the cell-free biosynthesis of guinea pig pancreas ribonuclease, we have developed an ion exchange procedure for its isolation and have analyzed the various subcellular fractions with this technique. This cytological approach was independently applied in studies on the ribonuclease of mouse pancreas (1). Earlier studies on the pancreas of several species have indicated that ribonuclease is found among all the subcellular fractions (l-3). The guinea pig pancreas is not an exception, since almost one-half the enzyme activity is in the soluble supernatant (3). The presence of more than one pancreatic ribonuclease has been demonstrated in several laboratories by ion exchange chromatography (1,~8) .I,2 The chromatographic analysis of subcellular fractions of mouse or beef pancreas has shown the presence of all these components and, furthermore, has shown the same relative amount of each ribonuclease component except in the soluble supernatant (1, 4, 5). In this fraction, a poorly retained component was present which was readily decomposed during the isolation procedure and gave the original two components (4,5). The more strongly adsorbed ribonuclease component is usually present in the highest amounts with the proportion varying from 90% in bovine pancreas to 65% in guinea pig pancreas. The large proportion of ribonuclease B3 in guinea pig pancreas seems due to the presence of a new ribonuclease component which differs from the poorly retained component of mouse pancreas (1) in that dialysis or acid treatment yields only the ribonuclease B.