alpha,beta-unsaturated aldehydes accelerate oxymyoglobin oxidation

This study investigates the potential basis for enhancement of oxymyoglobin (OxyMb) oxidation by lipid oxidation products. Aldehydes known to be forme d as secondary lipid oxidation products were combined with OxyMb in aqueous solution at 37 degrees C and pH 7.4. Metmyoglobin (MetMb) formation was gr eater in the presence of alpha,beta-unsaturated aldehydes than their satura ted counterparts of equivalent carbon chain length. Additionally, increasin g chain length from hexenal through nonenal resulted in increased MetMb for mation (P < 0.05). Electrospray ionization mass spectrometry (ESI-MS) revea led that OxyMb incubated with 4-hydroxynonenal (HNE) at pH 7.4 at 37 degree s C yielded myoglobin molecules adducted with one to three molecules of HNE from 0.5 to 2 h of incubation, respectively. A prooxidant effect of HNE wa s noted at pH 7.4 but was not apparent at pH 5.6 when compared to the contr ol (P < 0.05). This appeared to be due to rapid OxyMb autoxidation at this pH compared to pH 7.4. ESI-MS demonstrated that adduction of HNE to OxyMb o ccurred at pH 5.6. This research demonstrates that alpha,beta-unsaturated a ldehydes accelerate OxyMb oxidation and appear to do so via covalent attach ment.