Recombinant human neutrophil leukotriene B-4 (LTB4) omega-hydroxylase (cytochrome P450 4F3) has been purified to a specific content of 14.8 nmol of P450/mg of protein from yeast cells. The purified enzyme was homogenous as judged from the SDS-PAGE, with an apparent molecular weight of 55 kDa, The enzyme catalyzed the omega-hydroxylation of LTB4 with a K-m of 0.64 mu M and V-max of 34 nmol/min/nmol of P450 in the presence of rabbit hepatic NADPH-P450 reductase and cytochrome b(5). Furthermore, various eicosanoids such as 20-hydroxy-LTB4, 6-trans-LTB4, lipoxin A(4), lipoxin B-4, 5-HETE and 12-HETE, and la-hydroxy-stearate and omega-hydroxyoleate were efficiently omega-hydroxylated, although their K-m values were much higher than that of LTB4. In contrast, no activity was detected toward laurate, palmitate, arachidonate, 15-HETE, prostaglandin A(1), and prostaglandin E-1, all of which are excellent substrates for the CYP4A fatty acid omega-hydroxylases, This is the first time human neutrophil LTB4 omega-hydroxylase has been isolated in a highly purified state and characterized especially with respect to its substrate specificity. (C) 1998 Academic Press.
