Cryptoregiochemical analysis of an unusual bacterial desaturation

The cryptoregiochemistry of the cold-induced Δ5 desaturation of long chain fatty acids, as it occurs in Bacillus subtilis ATCC 23857, has been examined by measuring the individual primary deuterium kinetic isotope effects associated with the C–H bond cleavage at C-5 and C-6. The results point to C-5 as the site of initial oxidation in Δ5 desaturation.