Comparative optically detected magnetic resonance studies of mammalian phospholipase A2-lipid interactions.
A major difference between porcine and bovine pancreatic phospholipase A2 (PA2) is the relatively low affinity of the bovine enzyme for lipid-water interfaces. We have investigated the binding of porcine, bovine, and equine PA2 to n-hexadecylphosphocholine (C16-PC) micelles using optically detected magnetic resonance (ODMR) spectroscopy. The zero field splittings (ZFS) of the single Trp-3 residue undergo significant changes upon binding of PA2 to C16-PC micelles. ZFS titrations of PA2 vs C16-PC indicate that porcine and equine enzymes have similar binding affinity and stoichiometry, while bovine PA2 binds much more weakly to the lipid-water interfaces. This may be attributed to the differences in the amino acid composition and the conformation of the binding sites for lipid-water interfaces of these enzymes.
D000818:Animals; D002417:Cattle; D002794:Choline / Q000031:analogs & derivatives*; D006736:Horses; D007700:Kinetics; D008280:Magnetics; D008823:Micelles; D010179:Pancreas / Q000201:enzymology; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000378:metabolism; D011485:Protein Binding; D013045:Species Specificity; D013057:Spectrum Analysis; D013552:Swine
D008823:Micelles; D010767:Phosphorylcholine; C039128:miltefosine; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D002794:Choline