INVESTIGADORES
FIDELIO Gerardo Daniel
congresos y reuniones científicas
Título:
Secretory Phospholipase A2 from Glycine max: functional parameters and substrate preference
Autor/es:
MARIANI, M.E.,; MADOERY, R.,; FIDELIO G.D.
Lugar:
Tucumán, Argentina
Reunión:
Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofisica; 2012
Institución organizadora:
Sociedad Argentina de Biofisica
Resumen:
Phospholipase A2 catalyzes the
stereospecific cleavage of the sn-2
acyl ester union of diacyl-glycerophospholipids and liberates 1-acyl-2
lysophospholipids and free fatty acids. The
novel secretory Phospholipase A2 enzyme from soybean (Glycine max)(1), denoted
as GmsPLA2-I, has been characterized
with respect to substrate preference and
optimum conditions of catalysis. The effect of the head-group charge of the phospholipids substrate on
the GmsPLA2 catalyzed hydrolysis was examined through initial rate
kinetic measurements of the free fatty acid liberated by the enzyme activity towards
mixed micelles of phospholipid/Triton X-100 in a
Colorimetric assay. The substrates used in this studies were 1,2-dilauroyl-sn-glycero-3-phosphate (DLPA),1,2dilauroyl-sn-glycero-3-phosphoethanolamine
(DLPE) ,1,2-dilauroyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DLPG)
and dilauroylphosphatidylcholine (DLPC). The
optima of pH, temperature, and calcium concentration were found to be similar
to the parameters of secretory PLA2s from other plants and animals. However, substrate preferences
markedly differed. In contrast to pancreatic sPLA2(2), GmsPLA2-I
preferred zwitterionic phospholipids, and showed lower activity toward anionic
phospholipids. This way, the sPLA2-I enzyme shows more activity
towards PC > PE > PG > PA. Moreover, the kinetic parameters (Vmax and KM)
for DLPG and DLPC substrates were determined.