Simple and rapid method for the selective detection of individual lipoxygenase isozymes in soybean seeds

A simple and rapid spectrophotometric and visual judging method was developed for the selective detection of individual lipoxygenase isozymes (L-1, L-2, and L-3) in soybean [Glycine max (L.) Merrill] seeds, based on the bleaching activities of these isozymes in contact with methylene blue and beta-carotene. The method consists of three procedures designated tests I-III. The tests are performed by mixing soybean extract samples or wetted soybean flour with each dye-substrate of test I for the L-1 isozyme, test II for the L-2 isozyme, and test III for the L-3 isozyme, whereupon the presence of individual isozymes contained in the soybean is determined spectrophotometically or visually within 10 or 5 min, respectively. In the visual judging method available as a routine screening test, the total amount of soybean flour required for the three tests is only about 10 mg