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An enzyme caught in action: Direct imaging of hydrolytic function and domain formation of phospholipase A 2 in phosphatidylcholine monolayers
Author(s) -
Grainger D.W.,
Reichert A.,
Ringsdorf H.,
Salesse C.
Publication year - 1989
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 - 10.1016/0014-5793(89)80892-0
Subject(s) - dipalmitoylphosphatidylcholine , chemistry , phosphatidylcholine , phospholipase , hydrolysis , monolayer , enzyme , phospholipase d , phospholipase a2 , lipid bilayer , enzymatic hydrolysis , phospholipase c , phospholipase a , biochemistry , phospholipid , stereochemistry , membrane
Phospholipase A 2 , a ubiquitous lipolytic enzyme that actively catalyses hydrolysis of phospholipids, has been studied as a model for enzyme‐substrate reactions, as a membrane structural probe, and as a model for lipid‐protein interactions. Its mechanism of action remains largely controversial. We report here for the first time direct microscopic observation of the lipolytic action of fluorescently marked phospholipase A 2 ( Naja naja naja ) against phosphatidylcholine monolayers in the lipid phase transition region. Under these conditions, phospholipase A 2 is shown to target and hydrolyse solid‐phase lipid domains of L‐α‐dipalmitoylphosphatidylcholine. In addition, after a critical extent of monolayer hydrolysis, the enzyme itself aggregates into regular, visible proteinaceous domains within the lipid monolayer. Solid‐phase lipid hydrolysis indicates a preferential hydrolytic environment for phospholipase A 2 while enzyme domain formation points to a possible allosteric inhibition mechanism by hydrolysis products.