Hydrolysis of synthetic mixed-acid phosphatides by phospholipase A from human pancreas

Abstract

The Stale ~:)I*teXS~lrl' , IfZ*rchl (l-be .Vethcrlands3 ll{c~,-ivcd June 13th :c~2) SUMM \ NY An inve~tigation wa_~ made int~ the action of a human pancreatic phosph~lipase A on various synthetic ph~x~phatidcs. L-a-l)hosl)hatidyt ethanolamines were readily hydrolvsed in an aqueous system by this enzyme. Synthetic lecithin.,+, h,Jwever, were not attacked in an appreciable rate by the mammalian phospholipase A, contrary to the action J~f the enzymes from animal poisons. Addition of deoxycholate I or synthetic phosphatidic acid greatly enhanced the degradatiou of s~-nthetic lecithins by the pancreatic phospholipase A. The site of action of the human pancreatic phospholipase A was determined with the aid of mixed-acid lecithins and ph¢)sphatidyl ethanolamines containing it, different molecular positions combinati-ns of stearic and laurie acid, stearic and oleic acid, paknitic and linolentc aod, restw~ctively. Ihe enzyme was demonstrated to liberate always the fl-e:,~rified fatty acids while the ;e-attached fatty acid constituents were recovered in the pro;luted Iv~o cnrnpounds. Hence the mode of action of thi~ phospholipase A from hum;tn pancreas is identical to the action of the corresponding phnspholipase from animal poisons so far investigat-d. [NTI~ODUCTIOS Recently MAGEE et aL l purified pho.~pholipase A (ph~.~phatitle ac.vI-hydrolase, E.C. 3.1.I.4) from ]lUlnaFl pancreas. It js ur, kl]owtl which fatty acid t~¢ter bond of the ...... LIIg ldbl. phospholipid molecule is catalytically" hvdr.b,-m-d by this cu~vm,~. I Jr ,~., years phospholipase A from .snake venom (Crolahts adamantheus) has been demonstrated, contrary to earlier views, t~, act on the fl-~'ster position only ~-~. It cannot be. precluded that the mode of action of phospholipasc A from other biological origins might differ from the snake-venom enzyme b.v acting on v-ester or on both 7-and fl-ester positions of the phosphoglyceride molecule. For this reason a:~ h~vestigation was made on the site of action of the pancreatic paosphf~lipa.~: A, using ,,:ari<>us synthetic phospholipid suhstrates, containing within each molecule two different fatty acid constituents. * CoBt_rtbutio~ 1N'O. 3o in the series "'Metabolism and Functions of Phc~pha~des".

Evidence that the zymogen of phospholipase A2 binds to a negatively charged lipid-water interface

“…Two decades ago it was reported that hydrolysis of acidic phospholipids was more complete than hydrolysis of zwitterionic phospholipids, as judged by chromatographic analysis of the mixture after incubation with human PLA [9]. This apparent preference of pancreatic PLA for anionic phospholipids has been confirmed more recently by kinetic studies on monomolecular surface films [8,17].…”

“…So far, however, kinetic and direct binding studies supporting this hypothesis have been performed largely using either phosphatidylcholines as substrates or substrate analogs carrying the phosphocholine polar head group [7]. Thus the possible importance of lipid surface charge in the mechanism of action of PLA has remained obscure in spite of the fact that, in retrospect, there are clear indications in the older literature [9], that lipid-protein charge interactions might play a role in PLA function.…”

How to Make a Barrett Esophagus: Pathophysiology of Columnar Metaplasia of the Esophagus

“…Lysolecithin is formed when pancreatic phospholipase A hydrolyzes the lecithin in bile (49). Its role in the occurrence of BE is by far less understood than that of acid and bile salts but some studies have demonstrated that lecithin is a potentially harmful agent to the esophageal mucosa.…”

Structural, functional, and bioinformatics studies reveal a new snake venom homologue phospholipase A2 class

“…Phospholipases A 2 (PLA 2 s) are small (∼14kDa), stable, calcium‐dependent, disulfide‐rich enzymes that cleave membrane phospholipids at the sn ‐2 position, producing lysophospholipids and free fatty acids 1. The released fatty acids can function as energy stores, second messengers2, 3 and precursors of eicosanoids, which are potent mediators of inflammation 4, 5.…”