Interfacial binding dynamics of bee venom phospholipase A\u3csub\u3e2\u3c/sub\u3e investigated by dynamic light scattering and quartz crystal microbalance

Bee venom phospholipase A2 (bvPLA2) is part of the secretory phospholipase A2 (sPLA2) family whose members are active in biological processes such as signal transduction and lipid metabolism. While controlling sPLA2 activity is of pharmaceutical interest, the relationship between their mechanistic actions and physiological functions is not well understood. Therefore, we investigated the interfacial binding process of bvPLA2 to characterize its biophysical properties and gain insight into how membrane binding affects interfacial activation. Attention was focused on the role of membrane electrostatics in the binding process. Although dynamic light scattering experiments indicated that bvPLA2 does not lyse lipid vesicles, a novel, nonhydrolytic activity was discovered.Weemployed a supported lipid bilayer platform on the quartz crystal microbalance with dissipation sensor to characterize this bilayer-disrupting behavior and determined that membrane electrostatics influence this activity.The data suggest that (1) adsorption of bvPLA2 tomodelmembranes is not primarily driven by electrostatic interactions; (2) lipid desorption can follow bvPLA2 adsorption, resulting in nonhydrolytic bilayer-disruption; and (3) this desorption is driven by electrostatic interactions. Taken together, these findings provide evidence that interfacial binding of bvPLA2 is a dynamic process, shedding light on how membrane electrostatics can modulate interfacial activation. © 2010 American Chemical Society