Arachidonate 5-lipoxygenase of guinea pig peritoneal polymorphonuclear leukocytes. Activation by adenosine 5'-triphosphate.

Arachidonate 5-lipoxygenase was isolated from guinea pig peritoneal polymorphonuclear leukocytes, and partially purified from a high speed supernatant of a homogenate. 5-Hydroperoxy-6,8,11,14-eicosatetraenoic acid was a predominant reaction product. The enzyme reaction required specifically calcium ion (20 microM for half-maximal activity), and other divalent cations such as magnesium and cobalt were ineffective. The calcium-dependent 5-lipoxygenase reaction was stimulated by several nucleotides, most prominently by ATP in the order of 1 mM. 5,8,11,14,17-Eicosapentaenoic acid as substrate was as active as arachidonic acid, and was oxygenated at the C-5 position.