Antioxidant protein with alkyl hydroperoxidase activity. Required for the reduction of the AhpC active site cysteine residues and for the regeneration of the AhpC enzyme activity. Together with AhpC, DlaT and Lpd, constitutes an NADH-dependent peroxidase active against hydrogen and alkyl peroxides as well as serving as a peroxynitrite reductase, thus protecting the bacterium against reactive nitrogen intermediates and oxidative stress generated by the host immune system. (R)-N(6)-dihydrolipoyl-L-lysyl-[lipoyl-carrier protein] + a hydroperoxide = (R)-N(6)-lipoyl-L-lysyl-[lipoyl-carrier protein] + an alcohol + H2O Optimum pH is 7.2. Homotrimer. Identified in a complex with AhpC, DlaT and Lpd. Belongs to the AhpD family.