Investigating redox instability induced by 4-hydroxynonenal: A comparison between porcine and bovine myoglobins

Myoglobin (Mb) redox stability is influenced by several factors, including reactive lipid oxidation products. 4-Hydroxy-2-nonenal (HNE) is an α,β-unsaturated aldehyde formed from the oxidation of ω-6 polyunsaturated fatty acids. HNE is very reactive to proteins, and accelerated oxidation of oxymyoglobin (OxyMb) derived from several animal species. This research investigated the potential species-specific interactions between Mb and HNE, to determine the preferential HNE adduction in Mb from two different meat-producing livestock species, and to compare HNE-induced redox instability in equine OxyMb and equine carboxymyoglobin (COMb). Using MALDI-TOF MS it was determined that bovine Mb is more susceptible to nucleophilic attack and subsequent adduction by HNE than porcine Mb. LC-ESI-MS-MS and quantitative proteomics analyses revealed that HNE adduction happened exclusively at histidine (HIS) residues in porcine and bovine Mb, in a species-specific manner. Our findings indicated that COMb is susceptible to HNE-induced browning in a pH- and temperature-dependent manner.