Reduction of alkyl hydroperoxides to alcohols: role of rubredoxin, an electron carrier in the bacterial hydroxylation of hydrocarbons.

Alkyl hydroperoxides are reduced to alcohols in the presence of DPNH and homogeneous rubredoxin and rubredoxin-DPN reductase from Pseudomonas oleovorans. The reaction does not occur when TPNH is substituted for DPNH or when rubredoxins from anaerobic bacteria are substituted for the P. oleovorans nonheme iron protein. The reaction appears to have broad substrate specificity; 1-octyl, 2-octyl, cyclohexyl, and cumyl hydroperoxides are all reduced at significant rates. The reduction of alkyl hydroperoxides is inhibited by cyanide, as is the hydroxylation of alkanes and fatty acids in the same enzyme system supplemented with the w-hydroxylase. Previous studies in this laboratory have shown that alkanes (1,2) and fatty acids (3,4) undergo hydroxylation in enzyme preparations of Pseudomonas oleovorans according to the equation: RCH3 f DPNH + H+ + 02+RCH20H + DPN+ + H20. The three enzymes found to be required in the overall reaction (5) were purified and identified as rubredoxin (6,7) rubredoxin-DPN reductase (a), and an o-hydroxylase (9). In the present paper evidence is presented that rubredoxin serves as an electron carrier in the reduction of alkyl hydroperoxides to the corresponding alcohols. Hydroperoxides were apparently first suggested as intermediates in microbial hydrocarbon oxidations by Imelik (10) in 1948, and numerous investigators have subsequently proposed a role for hydroperoxides or have studied their fate