Activity profile of the first prokaryotic secretory phospholipase A2 acting on substrate monolayers

PABLO J. YUNES QUARTINO; GERARDO D. FIDELIO

San Javier - Tucumán

Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofísica; 2012

Secretory phospholipases A2 (sPLA2s) are small (13-15KDa), highlydisulfide-linked enzymes that hydrolyze the sn-2 ester bond ofglycerophospholipids, requiring Ca2+ in the millimolar range for activity.The most common features studied are head-group and chain lengthpreferences. However, data on activity vs. lateral packing of lipid substrateis not frequently found in the literature. It has been shown that there couldbe a remarkable difference between enzymes and this is related to its abilityto attack cell membranes. E.g. sPLA2 from pig pancreas hydrolyses dlPCmonolayers with a cut-off lateral pressure of 18 mN/m while cobra venomsPLA2 does it up to 30 mN/m. In turn, red blood cells are hydrolyzed bycobra sPLA2 but not by the enzyme of pancreatic origin.In 2002 a sPLA2 was obtained from Streptomyces violaceoruber cultures(1). This was the first sPLA2 of prokaryotic origin described in theliterature.In this work we present the first steps to characterizing the activity of thisenzyme in substrate monolayers of DLPC along with a comparison to thecanonical enzyme models of ?high? lateral pressure (cobra venom sPLA2)and ?low? lateral pressure (pig pancreatic sPLA2) enzymes. To obtain thecut-off and optimal pressures values we used the standard barostattechnique, and a simpler constant area analysis. Both approaches producedvery similar results.1. Sugiyama M., Ohtani K., Izuhara M., Koike T., Suzuki K., Imamura S., Misaki H.The Journal of B. Chemistry 277: 20051?20058 (2002)