Lipoxygenase of the thermophilic bacteria thermoactinomyces vulgaris—properties and study on the active site

Abstract

1. 1. A lipoxygenase activity was purified from Thermoactinomyces vulgaris and some of its properties were characterized. 2. 2. The enzyme showed a temperature activity range of 40–55°C with still significant activity over 60°C. 3. 3. The pH of activity on linoleic acid had a broad range with an optimum at pH 6.0 and a weaker one at pH 11.0. 4. 4. On arachidonic acid the pattern was narrow bell-shaped with an optimum at pH 6.5. 5. 5. The purified lipoxygenase from Th. vulgaris showed an apparent K m of 1 mM and V max of 0.84 μmol diene/min/mg protein. 6. 6. It was inhibited by the oxidation products, 9-HPOD and 13-HPOD. 7. 7. A 160,000 Da molecular weight of the enzyme was determined by molecular filtration. Methionine, tyrosine, tryptophan and cysteine are apparently involved in its activity.