Isolation and Properties of Prophosholipase A2 from Ox and Sheep Pancreas

Abstract

Two prophospholipase A fractions, having a similar amino acid composition but different isoelectric points, have been isolated from ox pancreas. Upon tryptic activation both zymogens release an identical heptapeptide located at the N-terminal part of the chain giving rise to the formation of two isoenzymes. From sheep pancreas also two prophospholipases A were purified. The latter zymogens, however, differ only in the amino acid composition of the activation peptide and they produce the same active enzyme upon tryptic activation. The ruminant phospholipases show a strong resemblance in amino acid composition and kinetic behaviour, but they differ markedly from the porcine enzyme as regards pH optimum, specific activity and affinity for lipid/water interfaces.