ISOENZYMES OF LIPOXIDASE

A polyacrylamide disc gel electrophoretic technique is described for studying isoenzymes or multiple molecular forms of lipoxidase in extracts of fresh green peas, pea seeds, wheat, fresh green beans and green bean seeds. After electrophoresis, gels containing starch were incubated with linoleic acid. Hydroperoxide bands were visualized by treating the gel with acidic potassium iodide. Staining specificity was established using the following criteria. Activity was absent when extracts or gels were boiled and when linoelaidic and oleic acids were used as substrates. Cyanide did not inhibit staining, whereas α-tocopherol, hydroquinone and nordihydroguaiaretic acid did. Prevention of the appearance of artifactual bands was attempted by: pre-electrophoresis of the gels; electrophoresis in the presence of thioglycollic acid; elimination of the large pore gel; pH adjustment of the plant extracts; and extraction of extract solids with lipid solvents. Gel patterns indicated two to three lipoxidase bands for fresh green peas and pea seeds, one to two bands for fresh green beans and green bean seeds, and four bands for wheat. © 1969 American Oil Chemists' Society.