PURIFICATION AND PROPERTIES OF AN ANIONIC ZYMOGEN OF PHOSPHOLIPASE A FROM PORCINE PANCREAS

1. 1. This paper describes the isolation and purification of an enzymically inactive precursor of porcine pancreatic phospholipase A (phosphatide acyl-hydrolase, EC 3.1.1.4). 2. 2. The protein, which has a molecular weight of about 15 000, appears to consist of a single polypeptide chain, terminating at the NH2 region in the amino acid sequence: Glu-Gly-Glu-Ile-Ser-Ser-Arg-Ala......, and having cystine as COOH-terminal amino acid. 3. 3. The precursor molecule is activated by trypsin which splits the above -Arg-Ala-peptide bond, yielding active phospholipase A and the heptapeptide: Glu-Gly-Glu-Ile-Ser-Ser-Arg. 4. 4. In this released peptide, as well as in the precursor molecule itself, the N-terminal glutamic acid residue has no free α-NH2 group. 5. 5. Phospholipase A, isolated from autolysed pancreatic tissue, appears to be identical with the product obtained by trypsin activation of the pure precursor. © 1968.