Lipoxygenase From Tomato Fruit: Partial Purification and Study of Some Properties

The activity of lipoxygenase extracted from tomato fruits can be twice as important according to tomato varieties. Differences between the last stages of ripening agree with the results previouslv reported. The partially purified enzyme (27‐fold) is very unstable and can be protected during a limited time by ascorbic acid and EDTA. The fact that it is inhibited by hydrogen peroxide and not by cyanide ions (10 ‐3 M) and EDTA (10 ‐3 M) is in favor of a true lipoxygenase and not a hematin compound. The molecular weight of the enzyme was estimated from gel filtration to be approximately 87,000. The enzyme had a pH optimum at 6.3–6.5 and a maximum activity at 40°C. The apparent K m determined in the presence of ethanol is 0.015 μM.