Isolation and properties of prophospholipase A2 from human pancreatic juice

Studies on Prophospholipase A2 and Its Enzyme from Human Pancreatic Juice

“…The possibility of an histidine residue in the active site of human phospholipase A was strongly suggested by the velocity/pH dependence previously observed [9]. In order to confirm this result we have studied the interaction of the human enzyme with l-bromo-2-octanone, a haloketone possessing similar inhibitory properties as p-bromophenacyl bromide.…”

“…With the exception of a partial immunological identity already described between human and porcine enzymes [9], no line of precipitation could be visualized between human phospholipase A2 and the antisera to the other mammalian phospholipases, nor between these various mammalian homologous enzymes with the antiserum to human phospholipase A2. of the porcine enzyme assayed under the same conditions.…”

“…These results led us to conclude that the pH optimum of the human enzyme is closer to pH 6.0 than to pH 8.0. The pH optimum of 8.0 previously found with the egg yolk test system [9] is probably simply due to the fact that bile salts loose their emulsifying action at more acidic pH.…”

“…Pure human prophospholipase AZ was prepared from pancreatic juice by the previously described method [9].…”

“…These results further confirm the correlation between a very precise architecture of the N-terminal region of the phospholipases and their interactions with lipid/water interfaces. We already mentioned [9] that the specific activity of the human enzyme in the egg yolk test, (600 ymol . min-I .…”