The Isolation and Properties of Two Prephospholipases A₂ from Porcine Pancreas

Prephospholipase A 2 , when isolated via the procedure described previously, by us in 1968, has pyroglutamic acid as the N‐terminal amino acid. However, this could be an artifact due to the drastic conditions of one of the early stages of the purification. Therefore a milder procedure has been developed in order to check whether or not pyroglutamic acid is artifactual. During these experiments two forms of prephospholipase A 2 were purified: one (form II) being identical with the one already described, the other (form I) having a shorter activation peptide, i.e. Ser‐Ser‐Arg instead of <Glu‐Glu‐Gly‐Ile‐Ser‐Ser‐Arg. Evidence is given that this is the only difference between forms II and I and that elastase can be responsible for the specific conversion of form II to form I by release of the N‐terminal tetra‐peptide of form II. No carbohydrates could be detected in any of the preparations.