Enzymatic formation of 9,16-dihydro(pero)xyoctadecatrienoic acid isomers from alpha-linolenic acid.

Incubation of alpha-linolenic acid with soybean lipoxygenase at pH 6.5 led to formation of conjugated triene oxidation products exhibiting maximum uv absorption at 267 nm, which were converted into four 9,16-dihydroxyoctadecatrienoic acid isomers. In the precursor-substrate study, it seems that 9,16-dihydroxy acid isomers are derived from the doubly oxygenated products and the epoxide intermediate, which are both produced from hydrogen removal at C-14 of 9(S)-hydroperoxyoctadecatrienoic acid. Optimum pH and Km values for soybean lipoxygenase-1-catalyzed conversion of 9(S)-hydroperoxyoctadecatrienoic acid into the conjugated triene products were 8.5 and 80 microM, respectively.