The action of proteolytic enzymes and protaminase on salmine sulfate.

The possible rBle of protamines as intermediates in the enzymatic hydrolysis of proteins has held the interest of a number of investigators since the discovery of these basic polypeptides by Miescher (I , 2) in the sperm of fish. This class of polypeptides resembles genuine proteins quite closely with respect to molecular weight (approximately 3000) and presence of peptide linkages connecting the various amino acid residues, yet differs from proteins in that only a few species of amino acids are present. Therrfore protamines were thought to lend themselves admirably to the stud:, of substrate specificity of proteolytic enzymes. Moreover, it was felt that the structure of protamines could be elucidated further by the use of proteolytic enzymes. It was with this in mind that Kossel and Matthdws (3) reported that salmine and sturin were hydrolyzed by crude trypsin preparations but not by pepsin, and Waldschmidt-Leitz and Harteneck (4) reported that erepsin did not utilize protamines as substrates. These result’s indicate that protaminolytic activity is associated wit,h the trypsin fraction of pancreatic extracts. Waldschmidt-Leitz and coworkers (5, 6) reported the isolation of an enzyme which was capable of hydrolyzing protamines, though unable to act on proteins. Their findings led them to abandon their former hypothesis that trypsin could split protamines. Northrop (7), however, was unable to separate protaminase from chymotrypsin. The isolation of crystalline trypsin and chymotrypsin by Northrop and Kunitz (8,9) enabled Waldschmidt-Leitz and Akabori (10) to reinvestigate the action of proteinases on protamines and their degradation products. Thus, Waldschmidt-Leitz and Akabori compared their own proteinase preparation with the crystalline enzyme preparation of Northrop and Kunitz (8, 11) and studied the effect of these enzymes with respect to t,he liberation of amino nitrogen on casein, sturin, clupein, and clupean. Their findings indicate that the non-crystalline proteinase contained impurities and that clupean: the degradation product of clupein, is split more extensively than the native protamine. In 1935 Holter, Kunitz, and