1.13.11.77 evolution linoleate 10S-dioxygenase is an ancient relative of cyclooxygenase in cyanobacteria, linoleate 10S-dioxygenase works in tandem with a catalase-related protein with specific 10S-hydroperoxide lyase activity. Neighboring cyanobacterial genes, dioxygenase and catalase, are identified as linoleate 10S-dioxygenase and 10Shydroperoxide lyase, respectively. The Nostoc linoleate 10S-dioxygenase, the sequence of which contains the signature catalytic sequence of cyclooxygenases and fungal linoleate dioxygenases (YRWH), appears to be a heme dioxygenase ancestor 745297 1.13.11.77 metabolism the immediate downstream gene, Np-cat, encodes a specific linoleate 10S-hydroperoxide lyase (10S-hydroperoxyoleate being metabolized at only 3% of the rate) converting the product of Np-diox and working in tandem with it 745297 1.13.11.77 physiological function enzyme Np-diox is an oleate and linoleate heme 10S-dioxygenase-alpha-linolenate is also efficiently metabolized at lower concentrations, but it much more rapidly leads to enzyme inactivation 745297 1.13.11.77 physiological function the enzyme can be utilized by bacteria to detoxify free fatty acids released by wounded diatoms in the presence of copepods 765305