Mammalian Arachidonic Acid 15-Lipoxygenases: Fed-Batch Fermentation, Enzyme Purification and Functional Characterization.

BACKGROUND: Mammalian arachidonic acid lipoxygenases (ALOXs) are non-heme iron-containing enzymes that oxygenate polyunsaturated fatty acids (PUFAs) with at least two isolated double bonds to hydroperoxy derivatives. The patho-physiological roles of these enzymes in inflammatory, hyperproliferative, and neurological diseases have made them promising targets for pharmacological interventions. Unfortunately, the expression levels of ALOX isoforms in mammalian cells are very low, which makes functional characterization of native enzymes and the development of isoform-specific inhibitors challenging. METHODS: Here, we developed a unifying experimental protocol for fed-batch fermentation of mammalian ALOX isoforms in a bioreactor, followed by purification of the recombinant proteins and their functional characterization. RESULTS: Our methodological protocol allowed the preparation of mg amounts of catalytically active human ALOX15, mouse Alox15 and human ALOX15B. The purified proteins are suitable for high-throughput inhibitor screening assays but can also be used as antigens for the preparation of isoform-specific antibodies and for direct structural analyses. Antibodies cross-reacting with human ALOX15 and ALOX15B have been detected in the blood of patients suffering from colorectal cancer. CONCLUSIONS: Our functional ALOX data stresses the catalytic differences between mouse and human ALOX15 orthologs, and these catalytic peculiarities need to be considered when the results of mechanistic studies obtained in mouse models of human diseases are transferred to the human situation.