Detection of 4-hydroxy-2-nonenal adducts of turkey and chicken myoglobins using mass spectrometry

4-Hydroxy-2-nonenal (HNE), an unsaturated aldehyde generated by peroxidation of polyunsaturated fatty acids, is highly reactive and destabilizes myoglobin (Mb) redox state, affecting meat colour. Our objective was to characterise the adduction of HNE to turkey and chicken Mbs using tandem mass spectrometry (MS/MS). Turkey and chicken oxymyoglobins (OxyMbs) were incubated with HNE at 25 °C, pH 5.8 or 7.4. MetMb formation was greater in the presence of HNE than controls (p < 0.05). Electrospray ionisation-Q-TOF mass spectrometry of HNE-reacted Mbs revealed covalent adduction of HNE to both turkey and chicken Mbs via Michael addition. LC–ESI-MS/MS of chicken Mb reacted with HNE identified covalent adduction of histidine (His) residues 64 and 93 at pH 7.4, whereas at pH 5.8 only His 64 was adducted. These results suggest that HNE accelerates chicken OxyMb oxidation in vitro by covalent modification at histidine residues.