FIGURE 5.

Acetylation at H4K5, H4K8, H4K12, and H4K16. a, mass spectra of a histone H4 peptide (Gly⁴-Arg¹⁷) from different experimental groups (treated with 5 mm glucose, 30 mm glucose and 30 mm glucose, and minocycline). The doubly charged peaks m/z 719.9, 720.9, 721.9, 722.9, and 723.9 represent the peptide species that carry four ¹²C₂-, three ¹²C₂- and one ¹³C₂-, two ¹²C₂- and two ¹³C₂-, one ¹²C₂- and three ¹³C₂-, and four ¹³C₂-acetyl groups, respectively. b, representative tandem mass spectrum of the peptide. c, close views of the singly charged b₃, b₅, y₅, and y₇ ions from the different experimental groups. The b₃ peaks m/z 285.2 and 287.2 carry a ¹²C₂- and ¹³C₂-acetyl group, respectively. The b₅ peaks m/z 512.3, 514.3, and 516.3 carry two ¹²C₂-, one ¹²C₂- and one ¹³C₂-, and two ¹³C₂-acetyl groups, respectively. The y₅ peaks m/z 530.3 and 532.3 carry a ¹²C₂- and ¹³C₂-acetyl group, respectively. The y₇ peaks m/z 757.4, 759.4, and 761.4 carry two ¹²C₂-, one ¹²C₂- and one ¹³C₂-, and two ¹³C₂-acetyl groups, respectively. d, changes of acetylation at H4K5, H4K8, H4K12, and H4K16.