Comparative optically detected magnetic resonance studies of mammalian phospholipase A2‐lipid interactions

[摘要]

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.

[学科分类] 生物化学/生物物理

[关键词] ODMR;Phospholipase A2;Protein-lipid interaction;Tryptophan;C16-PC;n-hexadecylphosphocholine;CMC;critical micellar concentration;ODMR;optically detected magnetic resonance;PA2;pancreatic phospholipase A2;ZFS;zero field splittings