AUXINS ACTION ON Glycine max SECRETORY PHOSPHOLIPASE A2 ISMEDIATED BY THE INTERFACIAL PROPERTIES IMPOSED BY THE PHYTOHORMONES?.

MARIANI ME; MADOERY RICARDO; FIDELIO GERARDO

SIERRA DE LA VENTANA ( BS AS)

Congreso; XLIII REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE BIOFISICA (SAB); 2014

Sociedad Argentina de Biofisica (SAB)

AUXINS ACTION ON Glycine max SECRETORY PHOSPHOLIPASE A2 IS MEDIATED BY THE INTERFACIAL PROPERTIES IMPOSED BY THE PHYTOHORMONES Mariania,M.E, Madoeryb, R and Fidelioa,G.D aCentro de Investigaciones en Química Biológica de Córdoba, (CIQUIBIC, UNC?CONICET), Departamento de Química Biológica, Fac. de Cs. Químicas, Universidad Nacional de Córdoba. Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba. República Argentina bDepartamento de Fundamentación Biológica, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba, República Argentina Secretory phospholipase A2 (sPLA2) are soluble enzymes that catalyze the conversion of phospholipids to lysophospholipids and free fatty acids at membrane interfaces. The effect of IAA and IPA auxins on activity of recombinant sPLA2 isoforms from Glycine max was studied using membrane model systems including mixed micelles and Langmuir lipid monolayers. Both phytohormones shows to stimulate the activity of both plant sPLA2 using DLPC/Triton mixed micelles as substrate. To elucidate the mechanism of action of the phytohormones, we showed that both auxins are able to self penetrate lipid monolayers and cause an increment in surface pressure and an expansion of lipid/phytohormone mixed interfaces. The stimulating effect of auxins over phospholipase A2 activity was still present when using Langmuir mixed monolayers as organized substrate regardless of sPLA2 source (plant or animal). All the data suggest that the stimulating effect of auxins over sPLA2 is due to a more favorable interfacial environment rather to a direct effect over the enzyme. Acknowledgements:This work was supported by grants from SECyT-UNC, FONCYT-MinCyT and CONICET, Argentina.