Effect of 4-hydroxy-2-nonenal on myoglobin-mediated lipid oxidation when varying histidine content and hemin affinity

•HNE accelerated Mb-mediated lipid oxidation in washed muscle.•Increased histidine content in sperm whale Mb increased HNE-mediated lipid oxidation.•The combination of low hemin affinity and HNE increased lipid oxidation.•The likely sites of disruption in the Mb structure due to HNE adduction are described.

The compound 4-hydroxy-2-nonenal (HNE) dissolved in water was examined to remove potential effects of using ethanol to solubilize the aldehyde such as altering protein structure or redox properties of myoglobin (Mb). HNE became covalently bound to sperm whale Mb at up to five sites based on ESI-MS analysis. Adducted Mb promoted lipid oxidation in washed muscle more effectively than non-adducted Mb. Alkylation of P88H/Q152H Mb with HNE accelerated metMb formation and subsequent lipid oxidation. P88H/Q152H Mb exposed to HNE enhanced lipid oxidation compared to wild-type Mb exposed to HNE. Results using H97A Mb suggested that the combination of HNE and low hemin affinity facilitated rapid decomposition of preformed lipid hydroperoxides to secondary lipid oxidation products. HNE and HHE (4-hydroxy-2-hexenal) facilitated Mb-mediated lipid oxidation similarly. The potential mechanisms by which Mb binding of α,β-unsaturated aldehydes affect Mb oxidation and the onset of lipid oxidation are discussed.