Biochemical Characterization of Lipoxygenase Lacking Mutants,L-l-less,L-2-less,and L-3-less Soybeans

In this paper, lipoxygenase lacking mutants were characterized in comparison with normal soybeans. The three lipoxygenase isozymes (L-l, L-2, and L-3) in crude seed extracts of normal soybeans were resolved clearly by an improved SDS-polyacrylamide gel electrophoresis. As expected, the three mutant types, L-l-less (P. I. 408251 and 133226), L-2-less (P. I. 86023), and L-3 less (Wasenatsu and Ichigowase) soybeans did not give L-l, L-2, and L-3 protein bands, respectively on a single dimension SDS gel.

An anti L-2 serum obtained from a rabbit reacted not only with the purified L-2 protein, but also partially with the purified L-l and L-3 proteins. By double immunodiffusion and immuno-disc gel electrofocusing analyses using the anti L-2 serum, L-l, L-2, and L-3 isozymes could not be detected in crude seed extracts from P.I. 408251, P. I. 86023, and Wasenatsu soybeans, respectively.

Three lipoxygenase activity peaks (L-l, L-2, and L-3 enzyme peaks) and a small unknown activity peak eluted right after the L-l peak were fractionated by DEAE-Sephacel column chromatography of crude seed extracts of Raiden (normal) soybeans. The chromatographic analyses have demonstrated that both the L-l and the unknown enzyme activities disappear completely in the L-l-less type soybean seeds, and that the L-2 and L-3 enzyme activities disappear completely in P. I. 86023 and the L-3-less type soybean seeds, respectively.