Effects of petrosaspongiolide R on the surface topology of bee venom PLA(2): a limited proteolysis and mass spectrometry analysis.

Petrosaspongiolides are sponge metabolites belonging to the family of the gamma-hydroxybutenolide marine terpenoids. They possess a remarkable in vitro and in vivo anti-inflammatory profile, due to the specific inhibition of group II and III secretory phospholipase A(2) enzymes, and for this reason can be considered as potential lead for the development of anti-inflammatory drugs. The molecular mechanism of bee venom phospholipase A(2) inactivation has been identified, and the ligand-enzyme complex formation is guided by either non-covalent and covalent interactions. In this work we have analyzed the conformational changes induced by petrosaspongiolide R on the bee venom phospholipase A(2) topology during the molecular recognition process, through the application of limited proteolysis and mass spectrometric methodologies. The results are indicative of structural changes at the N- and C-terminal domains producing a more compact conformational arrangement of the enzyme.