Characterization of Purified Lipoxygenase Extracts from Fusarium proliferatum

A crude lipoxygenase (FI) extract from Fusarium proliferatum was partially purified by ammonium sulfate precipitation (FII). The purification of fraction FII by size-exclusion chromatography resulted in three major peaks, FIIIa, FIIIb, and FIIIc. Fraction FIIIa demonstrated the highest specific lipoxygenase activity as well as the highest recovery and was therefore further purified. The purification procedure resulted in one major fraction (FIV) by ion-exchange chromatography, and the presence of one major and two minor protein bands in both the native and sodium dodecyl sulfate−polyacrylamide gel electrophoresis patterns. The purified enzyme demonstrated approximately 2.5 times more activity toward mono- and dilinolein and 1.5 times more with linolenic and arachidonic acids than that exhibited toward linoleic acid at pH 6.0; however, at pH 10.5, this enzymatic fraction possessed an overall preference toward linoleic acid. The purified fraction produced mainly the 13-hydroperoxides (HPODs) from linoleic acid at pH 6.0 and the 9- and 13-HPODs, at a ratio of approximately 1:1, at pH 10.5. In addition, the presence of a lipoxygenase activity producing the 10- and 12-HPODs was also suggested at pH 10.5.