Positional specificity of oxygenation

Asymmetric hydroxylation of pentadienols by SLO-1 in eq. (19) has also been studied [262, 263]. It is suggested that the difference in the hydrophobic content between the proximal and distal groups significantly influences the positional specificity of oxygenation. 

The major lipoxygenases act at C-5, C-12 and C-15 (from the carboxyl terminus) of polyunsaturated fatty acids, but positional specificity of oxygenation can be variable (423). There is evidence that direct oxidation of one class of compound by lipoxygenase can lead to carbon-centered free radical-catalyzed cooxygenation of a second class (490), and that transcellular metabolism (491-495) or intracellular metabolism by different classes of oxygenases also occurs. Specific oxygenation at C-8 of arachidonic acid has also been induced in mammals (496) and is constitutive in some corals and starfish (497, 498). These factors complicate interpretation of phylogenetic relationships based on the presence of specific fatty acid metabolites. 

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