Identification of lipoxigenases in soy seeds [ Glycene Max (L.) Merrill ] of different ancestries. / Identificação de lipoxigenases em sementes de soja [Glycine max (L.) Merril] de diferentes linhagens.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The oxidative degradation of the soybean fatty acids which has taken place at the grain processing, have developed the flavor of green been or raw soybean. This degradation alters the palatability and consequently the acceptability of the products made by soybean, resulting in some industries problems. The lipoxygenase enzyme (linolenato: O2 oxirredutase, EC 1.13.11.12), which is the component that catalyze the reaction, exists in soybean in the shape of 3 isoenzymes characterized by 3 dominant genes, LOX-1, LOX-2 and LOX-3. The main propose of this work was the identification and qualitative and quantitative determination of the lipoxygenase fractions in Glycine max soybean seeds, which had come from the fourth generation of the first crossing (F4) of the mutants that didn?t have the respective LOX {PI-408251 (-LOX-1), PI-86023 (- LOX-2), TOHOKU no 74 (-LOX-3)}, using the commercial cultivar IAC-8, resulting in the seeds IAC 97-3503, IAC 97-3512, IAC 97-3545 and IAC 97-3808, which have been furnished by the Instituto Agronômico de Campinas (IAC). The qualitative and quantitative analysis of the samples were done beyond: 1)Electrophoresis in gel of poliacrilamida and SDS, to discriminate the existing bands; 2) color test and; 3) determination of the enzymatic activity using espectofotometric in the presence of: 3.1) specific subtracts and; 3.2) connected reaction of ?-carotene bleaching. It has been observed that beyond electrophoresis in gel each band corresponds to each isoenzyme. The oxidation reaction of LOX in the ?-carotene (LOX-3) and methyl blue (LOX-2 and LOX-1) was sensible for the detection of LOX-1 and LOX-3. The method for determination of enzymatic activities with utilization of substrates (linoleic acid for LOX-1 and LOX-3, and methyl-linoleate acid for LOX-2) it was sensible for detection of LOX-1 and LOX-3. Beyond the reaction of the co-oxidation of ?-carotene by LOX-2 and LOX-3, it was possible to determinate all the isoenzymes, adding the final result which was obtained first beyond electrophoresis in gel of poliacrylamide, and it has been saw that beyond the crossing and backcrosses been made by the IAC, the seed IAC 97-3503 haven?t shown any activity of LOX-1, to he step of it hasn?t been observed any significant reduction (p<0,05) in the others seeds that had been studied. A significant reduction had been shown (p<0,05) in LOX-2 in the seeds IAC 97-3512 and IAC 97- 3545 when they were compared to the standard IAC 8-2. To LOX-3 it had been observed a significant reduction (p<0,05) in the seed IAC 97-3503, and no reduction had taken place in the others cultures three seeds.

ASSUNTO(S)

soybeans lipoxygenase lipoxigenases soja sabor flavor

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