EFFECT OF ANALYTICAL CONDITIONS IN THE DE TERMINATION OF LIPOXYGENASE-1 ACTIVITY IN SOYBEAN

In this work it was used full fat soybean flour - Glycine max (L.) Mer ril - obtained of the cultivar Davis, to study the effects of shaking, time and particle size on the extraction of lipoxygenase-1 and the ef fect of freezing time on the activity of this isozyme. The lipoxygenas e extraction was done with 0,3g of flour and 15ml of 0,02M tris-HCl bu ffer, pH 8,2 and sacharose 13%, at 4 degrees C. The sizes af the parti cles studied were: flour without reduction of the size, biger than 50, equal to 50, 60 and 80 mesh. The extraction times were: 20, 30, 40, 5 0 e 60 minutes. The freezing effect (-18 degrees C) of the flours and extracts an the activity of the lipoxygenases was studied after 0, 15, 30 and 45 days and, 0, 2, 5 and 10 days, respectivelly. The effects a f enzyme and substrate concentration were studied in the cultivars San ta Rosa, FT2 and Davis. The best results for the enzyme extraction wer e obtained with hour without reduction of the particle sire during 30 minutes without shaking. The activity in the flour without reduction o n the particle size and flour with 80 mesh particle size did not showe d statistical difference. The freezing storage during 15 days caused a reduction on the lipoxygenase activity of the 80 mash particle size f lour. The extract freezing during 2 days caused a decrease on the enzy me activity.