title: Activation of phospholipase A2 by 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine in vitro.
abstract: Oxidative stress leads to drastic modifications of both the biophysical properties of biomembranes and their associated chemistry imparted upon the formation of oxidatively modified lipids. To this end, oxidized phospholipid derivatives bearing an aldehyde function, such as 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine (PoxnoPC) can covalently react with proteins that come into direct contact. Intriguingly, we observed PoxnoPC in a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) matrix to shorten and abolish the lag time in the action of phospholipase A2 (PLA2) on this composite substrate, with concomitant augmented decrement in pH, indicating more extensive hydrolysis, which was in keeping with enhanced 90 degrees light scattering. The latter was abolished by the aldehyde scavenger methoxyamine, thus suggesting the involvement of Schiff base. Enhanced hydrolysis of a fluorescent phospholipid analogue was seen for PLA2 preincubated with PoxnoPC. Mixing PLA2 with submicellar (22 microM) PoxnoPC caused a pronounced increase in Thioflavin T fluorescence, in keeping with the formation of amyloid-type fibers, which were seen also by electron microscopy.
authors.affiliation: Helsinki Biophysics and Biomembrane Group, Medical Biochemistry, Institute of Biomedicine, University of Helsinki, Finland.
authors.forename: Christian
authors.initials: C
authors.lastname: Code
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Mahalka
authors.forename: Kristian
authors.initials: K
authors.lastname: Bry
authors.forename: Paavo K J
authors.initials: PK
authors.lastname: Kinnunen
mesh_terms: D000818:Animals; D001514:Bee Venoms / Q000201:enzymology; D052160:Benzothiazoles; D004789:Enzyme Activation / Q000187:drug effects; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D046912:Multiprotein Complexes / Q000648:ultrastructure; D018384:Oxidative Stress; D010713:Phosphatidylcholines / Q000494:pharmacology*; D054467:Phospholipases A2 / Q000378:metabolism* / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence; D013844:Thiazoles
chemical_list: C097369:1-palmitoyl-2-(9-oxononanoyl)-sn-glycero-3-phosphocholine; D001514:Bee Venoms; D052160:Benzothiazoles; D005456:Fluorescent Dyes; D046912:Multiprotein Complexes; D010713:Phosphatidylcholines; D013844:Thiazoles; C009462:thioflavin T; D054467:Phospholipases A2