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Partial coverage of phospholipid model membranes with annexin V may completely inhibit their degradation by phospholipase A 2
Author(s) -
Speijer Han,
Jans Sylvia W.S,
Reutelingsperger Chris P.M,
Hack C.Erik,
van der Vusse Ger J,
Hermens Wim Th
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01527-x
Subject(s) - phospholipid , phosphatidylethanolamine , phosphatidylserine , phosphatidylcholine , membrane , annexin , phospholipase a2 , chemistry , hydrolysis , biochemistry , annexin a1 , phospholipase , pi , biophysics , chromatography , enzyme , biology , cell
Phospholipase A 2 (PLA 2 )‐mediated hydrolysis of membrane phospholipids was measured by ellipsometry, and the inhibition of this process by annexin V was studied. Planar membranes, consisting of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine (PC/PE/PS; 54:33:13, on molar basis), were degraded by pancreatic PLA 2 , and the rate of hydrolysis was limited to about 0.7%/min. The influence of graded coverage of the membrane with annexin V was studied. The degree of PLA 2 inhibition was nonlinearly related to the amount of membrane‐bound annexin V, and binding of only 12% and 54% of full membrane coverage resulted in, respectively, 50% and 93% inhibition. These findings indicate that the inhibition of PLA 2 ‐mediated hydrolysis by annexin V cannot be simply explained by shielding of phospholipid substrates from the enzyme. Moreover, the present results leave room for a role of endogenous annexin V in regulating phospholipid turnover in the plasma membrane of parenchymal cells such as cardiomyocytes.