Methylation of biomolecules is involved in many biological processes, including signal transduction and regulation of transcription. The contributing methylating agents can originate from endogenous and exogenous sources (such as cigarette smoking). Human hemoglobin is easily accessible from blood and has been used as molecular dosimetry for chemical exposure. We recently developed a method for characterization and quantification of the extents of methylation and ethylation in hemoglobin by nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) under the selected reaction monitoring mode. Using this method, the relative extents of methylated and ethylated peptides in human hemoglobin were quantified in nonsmoking subjects with various ages. Among the nine methylation sites, we found that the extents of methylation were significantly higher in old subjects at the <i>N</i>-terminal and His-20 of α-globin, and at the <i>N</i>-terminal and Glu-26 of β-globin. Moreover, the extents of methylation at these sites were significantly correlated with the age of the subjects. On the other hand, no statistically significant difference was found in the ethylated peptides. Our results suggest that that age should be considered as a factor when studying methylated biomolecules as biomarkers in epidemiological studies.

Methylation in human hemoglobin is associated with age as analyzed by liquid chromatography tandem mass spectrometry

256th National Meeting (2018)

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