Fig. 1

Mass isotopomer distribution profiles of a tryptic peptide from histone H2A. LC-MS analyses were used to determine the isotope profile of the peptide vTIAQGGVLPNIQAVLLPkkTESHHk; the intensity of the M0 peak (i.e., monoisotopic, m/z 1001.57 with a charge state of 3+) was used to normalize the intensities of the other mass isotopomers. Samples were obtained from control animals (i.e., who did not receive any tracer, shaded bars) and from animals in the respective pair-fed (PF, open bars) and alcohol-fed (AF, solid bars) groups following 5 days of ²H₂O exposure. The mass isotopomer profile in PF animals reflects a more active turnover (i.e., incorporation of ²H) as compared to AF animals (which more closely resemble the control animals, representing a reduced turnover with limited incorporation of ²H). Data are shown as the mean ± sem, n = 3–4 animals per group