Purification and some properties of potato tuber lipoxygenase and detection of linoleic acid radical in the enzyme reaction.

Lipoxygenase (linoleate: oxygen oxidoreductase, EC 1. 13. 1. 13) from tubers of potato (Solanum tuberosum) was purified 210-fold with a specific activity of 25 units/mg protein, using DEAE-Sephadex column chromatography and preparative polyacrylamide gel electrophoresis. The purified enzyme was electrophoretically pure. Some properties of this enzyme were the same as those of potato lipoxygenase previously reported. The enzyme was inhibited by saturated alcohols and SH-reducing reagents as well as soybean lipoxygenase was. The trapped radical of linoleic acid in potato lipoxygenase reaction was detected by ESR spectroscopy, using 2-methyl-2-nitrosopropane as a radical scavenger. Those suggest that the reaction of potato lipoxygenase proceeds by a very similar mechanism to soybean lipoxygenase.