Table II. A listing of all of the combinatorial histone codes found and further validated in the butyrate-treated histone H4 analysis shown in Figs. 8–10.
The annotated form is shown in column 1. An approximate percent abundance (Approx. percent abund.) is shown in column 2. This value is based on the sum of all precursor ion intensities that exhibit each histone code multiplied by an approximation of the fraction of the resulting ETD spectrum that the histone code represents based on the ratios of fragment ions. This information is presented for qualitative purposes only; however, we expect to be able to use such an approach in semiquantitative analyses with further validation. The m/z of the precursor ion is given in column 3, and in column 4 the number of methyl equivalents with which the m/z value correlates is shown where an acetylation counts as three methyl equivalents. In column 5 the retention time of the histone code is given.
| Histone code | Approx. percent abund. | m/z | Methyl eq | Retention time |
|---|---|---|---|---|
| min | ||||
| N-acK20me2 | 17.5 | 487.4 | 5 | 102.1 |
| N-acK12acK16acK20me2 | 15.9 | 504.2 | 11 | 62.7 |
| N-acK16acK20me2 | 13.1 | 495.7 | 8 | 78.0 |
| N-acK5acK8acK12acK16acK20me2 | 8.7 | 521.0 | 17 | 42.6 |
| N-acK12acK20me2 | 6.3 | 495.7 | 8 | 80.8 |
| N-acK5acK12acK16acK20me2 | 4.8 | 512.5 | 14 | 52.0 |
| N-acK8acK16acK20me2 | 3.1 | 504.1 | 11 | 64.6 |
| N-acK5acK8acK12acK16ac | 2.8 | 515.4 | 15 | 44.8 |
| N-acK5acK8acK16acK20me2 | 2.3 | 512.5 | 14 | 54.1 |
| N-acK5acK16acK20me2 | 2.3 | 504.2 | 11 | 66.4 |
| N-acK5acK12ac | 2.3 | 498.5 | 9 | 71.4 |
| K5acK8acK12acK16acK20me2 | 2.1 | 512.5 | 14 | 52.1 |
| K5acK8acK16acK20me2 | 1.8 | 504.2 | 11 | 64.1 |
| N-acK8acK20me2 | 1.7 | 495.7 | 8 | 83.2 |
| N-acK8acK12acK16acK20me2 | 1.6 | 512.5 | 14 | 50.3 |
| N-acK5acK20me2 | 1.5 | 495.9 | 8 | 85.2 |
| K8acK12acK16acK20me2 | 1.5 | 504.2 | 11 | 64.6 |
| K5acK16acK20me2 | 1.2 | 495.8 | 8 | 77.9 |
| N-acK8acK12acK20me2 | 1.1 | 504.2 | 11 | 68.9 |
| N-acK5acK12acK20me2 | 1.1 | 504.1 | 11 | 69.9 |
| K16acK20me2 | 1.0 | 487.3 | 5 | 94.4 |
| N-acK5acK8acK12acK16acK20me3 | 0.76 | 524.1 | 18 | 40.7 |
| N-acK5acK8acK12acK20me2 | 0.71 | 512.5 | 14 | 57.8 |
| N-acK5acK12acK16ac | 0.57 | 507.0 | 12 | 53.6 |
| N-acK5acK12acK20me1 | 0.56 | 501.3 | 10 | 70.2 |
| N-acK5acK8acK20me2 | 0.40 | 504.1 | 11 | 72.6 |
| N-acK12acK16acK20me3 | 0.38 | 507.0 | 12 | 62.3 |
| N-acK5acK8acK12ac | 0.37 | 506.9 | 12 | 59.1 |
| K12acK20me2 | 0.26 | 487.4 | 5 | 97.0 |
| N-acK16acK20me3 | 0.23 | 498.7 | 9 | 77.1 |
| N-acK8acK12acK16acK20me3 | 0.21 | 515.7 | 15 | 50.6 |
| K12acK16acK20me2 | 0.20 | 495.8 | 8 | 76.6 |
| N-acK5acK8acK12acK16acK20me1 | 0.19 | 518.4 | 16 | 43.9 |
| N-acK5acK8acK16ac | 0.16 | 506.9 | 12 | 55.7 |
| N-acK5acK12acK16acK20me3 | 0.15 | 515.5 | 15 | 51.0 |
| N-acR3me1K5acK8acK12acK16acK20me2 | 0.12 | 523.8 | 18 | 38.9 |
| K20me2 | 0.11 | 479.1 | 2 | 148.3 |
| N-acR3me2K5acK8acK12acK16acK20me2 | 0.073 | 526.7 | 19 | 39.3 |
| K8acK20me2 | 0.068 | 487.4 | 5 | 97.4 |
| N-acK5acK8acK12acK20me1 | 0.064 | 509.9 | 13 | 58.6 |
| N-acK12acK20me3 | 0.064 | 498.7 | 9 | 80.2 |
| N-acK12ac | 0.058 | 490.2 | 6 | 82.2 |
| N-acK20me3 | 0.053 | 490.3 | 6 | 98.7 |
| K5acK12ac | 0.049 | 490.3 | 6 | 82.5 |
| N-acR3me1K16acK20me2 | 0.046 | 498.7 | 9 | 76.2 |
| K5acK12acK16acK20me2 | 0.039 | 504.2 | 11 | 65.5 |
| N-acR3me1K8acK12acK16acK20me2 | 0.038 | 515.5 | 15 | 49.8 |
| N-acK5acK16ac | 0.036 | 498.6 | 9 | 69.0 |
| N-acK16ac | 0.029 | 490.2 | 6 | 79.3 |
| N-acK5acK12acK16acK20me1 | 0.027 | 510.0 | 13 | 52.7 |
| N-acK5acK8acK16acK20me3 | 0.020 | 515.4 | 15 | 53.5 |
| N-acK5acK8acK16acK20me1 | 0.016 | 509.9 | 13 | 54.8 |
| min | ||||
| N-acR3me1K12acK16acK20me2 | 0.013 | 507.2 | 12 | 60.5 |
| N-acK8acK12ac | 0.011 | 499.0 | 9 | 71.3 |
| K5acK8acK12acK16ac | 0.0097 | 507.4 | 12 | 53.3 |
| N-acK8acK12acK20me1 | 0.0086 | 501.7 | 10 | 70.0 |
| K5acK20me2 | 0.0075 | 487.4 | 5 | 97.8 |
| K5acK12acK16acK20me3 | 0.0054 | 507.1 | 12 | 64.2 |
| N-acR3me1K20me2 | 0.0053 | 490.3 | 6 | 97.8 |
| N-acK5acK16acK20me1 | 0.0047 | 501.6 | 10 | 67.4 |
| N-acR3me1K5acK8acK16acK20me2 | 0.0046 | 515.5 | 15 | 49.8 |
| N-acK12acK20me1 | 0.0043 | 493.2 | 7 | 81.9 |
| N-acK5acK20me1 | 0.0040 | 493.1 | 7 | 85.7 |
| K8acK16acK20me3 | 0.0038 | 498.7 | 9 | 76.4 |
| N-acR3me1K5acK12acK16acK20me2 | 0.0021 | 515.5 | 15 | 49.7 |
| K5acK8acK12acK16acK20me3 | 0.0020 | 515.5 | 15 | 51.7 |
| N-acK8acK16acK20me3 | 0.0017 | 507.1 | 12 | 61.2 |
| K5acK8acK12acK16acK20me1 | 0.0012 | 510.0 | 13 | 52.7 |
| K8acK16acK20me2 | 0.0006 | 496.0 | 8 | 76.2 |
| K5acK16acK20me3 | 0.0003 | 498.1 | 9 | 76.4 |