Determinação da atividade das enzimas lipoxigenases (L1 e L3) em oito genótipos de soja desenvolvidos pela Embrapa Soja

Abstract

Soybeans are a good protein source, because their proteins have an appropriate balance of essential amino acids. Soy has also a good composition of minerals like iron, magnesium and phosphorus, and it is an oilseed that contains high levels of polyunsaturated fatty acids. When exposed to water stress these lipids undergo directly to an autocatalytic attack by atmospheric oxygen. The action of lipoxygenases on polyunsaturated fatty acids will produce compounds formed during this oxidation process are responsible for the characteristic flavor called undesirable "beany flavor". Lipoxygenases are four isoenzymes designated L1, L2, L3a and L3b, and the last two isozymes show homogeneous properties, so they are called as L3. The aim of this study was to determine the activity of lipoxygenases (L1 and L3) in soybean seeds of eight different genotypes developed by Embrapa Soja. The methodology used was spectrophotometry in the ultraviolet region. The absorbances were determined using a spectrophotometer. The data obtained were used to calculate the variation of optical density (ΔDO). The results obtained for enzyme activity showed no significant difference for the isoenzyme L3 among the genotypes analyzed. For isozyme L1, BR 0955277 RR1 breeding line showed the lowest enzyme activity, thus being a promising to become a suitable cultivar for human consumption.