INVESTIGADORES
FIDELIO Gerardo Daniel
congresos y reuniones científicas
Título:
KINETIC CHARACTERIZATION AND SUBSTRATE PREFERENCE OF GmsPLA2-XIA-1 and GmsPLA2-XIB-2 IN MODEL MEMBRANE SYSTEMS
Autor/es:
MARIANI M.E.,; MADOERY R.,; FIDELIO G.D.
Lugar:
VILLA CARLOS PAZ, CORDOBA
Reunión:
Congreso; XLII REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE BIOFISICA; 2013
Institución organizadora:
SOCIEDAD ARG DE BIOFISCA
Resumen:
This is the first time secretory
Phosphalipase A2 (sPLA2) enzymes from soybean seeds (Glycine
max), denoted as GmsPLA2-XIA-1 and GmsPLA2-XIB-2,
were produced by heterologous expression in E.coli, renatured from
inclusion bodies by guanidine treatment and purified by ion exchange
chromatography. Mixed
micelles of phospholipid/Triton X-100 were used in a Colorimetric assay in
order to obtain the optimum conditions for catalysis. Both sPLA2s showed a maximum enzyme
activity at pH 7, a requirement of Ca2+ essentially in micromolar
concentrations and optimum temperature for catalysis of 60ºC, similar parameters to those found in animals and plants.
These enzymes showed subtle differences in the preference for phospholipids
with different head groups in the presence and absence of NaCl. The apparent
kinetic parameters (Vmax app and Km
app) demonstrate that both enzymes have more preference for
phosphatidilcholine than for phosphatidylglycerol in contrast with the results
observed for pancreatic sPLA2.
Furthermore, the mode of catalysis was studied. The effect of auxins as indole 3-acetic acid and indole 3-propionic
acid were studied and shows to rapidly stimulate the conversion of
phosphatidylcholine to LPC and free fatty acid.