Table II. Peak assignments for high resolution ETD MS/MS spectrum of modified histone H4 as shown in Fig. 5.
For some higher mass peaks, the monoisotopic peak was not observed; therefore, higher isotopic peaks were used.
| Ion type | Ion no. | PTM(s) | Charge | m/z measured | MH+ measured | MH+ calculated | Error |
|---|---|---|---|---|---|---|---|
| Da | Da | ppm | |||||
| c | 3 | Acetyl | 1 | 360.199 | 360.199 | 360.199 | −1.11 |
| c | 4 | Acetyl | 1 | 417.220 | 417.220 | 417.221 | −1.44 |
| c | 5 | Acetyl | 1 | 545.315 | 545.315 | 545.315 | −0.92 |
| c | 5 | Acetyl | 2 | 273.161 | 545.315 | 545.315 | −0.86 |
| c | 6 | Acetyl | 1 | 602.336 | 602.336 | 602.337 | −1.00 |
| c | 6 | Acetyl | 2 | 301.672 | 602.336 | 602.337 | −1.61 |
| c | 7 | Acetyl | 1 | 659.358 | 659.358 | 659.358 | −0.76 |
| c | 7 | Acetyl | 2 | 330.183 | 659.358 | 659.358 | −0.86 |
| c | 8 | Acetyl | 1 | 787.453 | 787.453 | 787.453 | −0.51 |
| c | 8 | Acetyl | 2 | 394.230 | 787.452 | 787.453 | −1.23 |
| c | 9 | Acetyl | 1 | 844.474 | 844.474 | 844.475 | −0.71 |
| c | 9 | Acetyl | 2 | 422.740 | 844.474 | 844.475 | −1.50 |
| c | 9 | Acetyl | 3 | 282.163 | 844.474 | 844.475 | −1.11 |
| c | 10 | Acetyl | 1 | 957.558 | 957.558 | 957.559 | −0.52 |
| c | 10 | Acetyl | 2 | 479.282 | 957.557 | 957.559 | −1.74 |
| c | 11 | Acetyl | 1 | 1014.580 | 1014.580 | 1014.580 | −0.10 |
| c | 11 | Acetyl | 2 | 507.793 | 1014.579 | 1014.580 | −1.74 |
| c | 11 | Acetyl | 3 | 338.865 | 1014.580 | 1014.580 | −0.14 |
| c | 12 | Acetyl | 1 | 1142.676 | 1142.676 | 1142.675 | 0.18 |
| c | 12 | Acetyl | 2 | 571.841 | 1142.674 | 1142.675 | −1.20 |
| c | 12 | Acetyl | 3 | 381.563 | 1142.674 | 1142.675 | −1.00 |
| c | 13 | Acetyl | 1 | 1199.696 | 1199.696 | 1199.697 | −0.42 |
| c | 13 | Acetyl | 2 | 600.352 | 1199.696 | 1199.697 | −0.81 |
| c | 13 | Acetyl | 3 | 400.570 | 1199.695 | 1199.697 | −1.28 |
| c | 14 | Acetyl | 1 | 1256.719 | 1256.719 | 1256.718 | 0.80 |
| c | 14 | Acetyl | 2 | 628.862 | 1256.717 | 1256.718 | −1.01 |
| c | 14 | Acetyl | 3 | 419.577 | 1256.716 | 1256.718 | −1.38 |
| c | 15 | Acetyl | 1 | 1327.756 | 1327.756 | 1327.755 | 0.15 |
| c | 15 | Acetyl | 2 | 664.381 | 1327.754 | 1327.755 | −0.73 |
| c | 15 | Acetyl | 3 | 443.256 | 1327.753 | 1327.755 | −1.39 |
| c | 16 | Acetyl | 2 | 728.428 | 1455.848 | 1455.850 | −1.35 |
| c | 16 | Acetyl | 3 | 485.954 | 1455.848 | 1455.850 | −1.54 |
| c | 17 | 2 acetyl | 2 | 827.484 | 1653.961 | 1653.962 | −0.47 |
| c | 17 | Acetyl | 2 | 806.480 | 1611.952 | 1611.951 | 0.58 |
| c | 17 | Acetyl | 3 | 537.988 | 1611.948 | 1611.951 | −2.13 |
| c | 17 | Acetyl | 4 | 403.742 | 1611.945 | 1611.951 | −3.98 |
| c | 18 | Acetyl | 2 | 875.008 | 1749.009 | 1749.010 | −0.78 |
| c | 18 | Acetyl | 3 | 583.674 | 1749.009 | 1749.010 | −0.94 |
| c | 18 | Acetyl | 4 | 438.007 | 1749.005 | 1749.010 | −3.04 |
| c | 19 | Acetyl | 2 | 953.059 | 1905.111 | 1905.111 | −0.35 |
| c | 19 | Acetyl | 3 | 635.708 | 1905.109 | 1905.111 | −1.49 |
| c | 19 | Acetyl | 4 | 477.032 | 1905.107 | 1905.111 | −2.31 |
| c | 21 | Acetyl + dimethyl | 2 | 1080.657 | 2160.306 | 2160.306 | 0.01 |
| c | 22 | Acetyl + dimethyl | 3 | 758.467 | 2273.386 | 2273.390 | −2.00 |
| c | 23 | Acetyl + dimethyl | 3 | 810.500 | 2429.486 | 2429.491 | −2.16 |
| c | 23 | Acetyl + dimethyl | 4 | 608.128 | 2429.491 | 2429.491 | 0.04 |
| c | 24 | Acetyl + dimethyl | 3 | 848.846 | 2544.524 | 2544.518 | 2.42 |
| c | 26 | Acetyl + dimethyl | 3 | 924.552 | 2771.642 | 2771.645 | −1.19 |
| z | 8 | 1 | 854.428 | 854.428 | 854.428 | −0.47 | |
| z | 9 | 1 | 911.449 | 911.449 | 911.450 | −0.33 | |
| z | 10 | 1 | 1039.508 | 1039.508 | 1039.508 | −0.29 | |
| z | 11 | 1 | 1195.609 | 1195.609 | 1195.609 | 0.08 | |
| z | 11 | 2 | 598.308 | 1195.608 | 1195.609 | −1.15 | |
| z | 12 | 1 | 1323.709 | 1323.709 | 1323.704 | 3.32 | |
| z | 12 | 2 | 662.356 | 1323.704 | 1323.704 | −0.36 | |
| z | 13 | 1 | 1437.796 | 1437.796 | 1437.796 | 0.21 | |
| z | 13 | 2 | 718.897 | 1436.787 | 1436.788 | −1.09 | |
| Da | Da | ppm | |||||
| z | 14 | 1 | 1508.832 | 1508.832 | 1508.833 | −0.93 | |
| z | 14 | 2 | 754.416 | 1507.824 | 1507.825 | −0.97 | |
| z | 15 | 1 | 1670.894 | 1670.894 | 1670.889 | 3.17 | |
| z | 15 | 2 | 835.948 | 1670.888 | 1670.889 | −0.58 | |
| z | 16 | 1 | 1769.973 | 1769.973 | 1769.957 | 9.04 | |
| z | 16 | 2 | 885.482 | 1769.957 | 1769.957 | 0.02 | |
| z | 17 | 2 | 935.019 | 1869.030 | 1869.026 | 2.32 | |
| z | 17 | 3 | 623.679 | 1869.023 | 1869.026 | −1.20 | |
| z | 18 | 2 | 992.535 | 1984.062 | 1984.053 | 4.65 | |
| z | 19 | 2 | 1058.050 | 2115.092 | 2115.093 | −0.41 | |
| z | 19 | 3 | 705.702 | 2115.091 | 2115.093 | −0.87 | |
| z | 20 | 2 | 1093.565 | 2186.124 | 2186.130 | −3.01 | |
| z | 20 | 3 | 729.381 | 2186.129 | 2186.130 | −0.61 | |
| z | 21 | 2 | 1144.092 | 2287.176 | 2287.178 | −0.73 | |
| z | 21 | 3 | 763.064 | 2287.177 | 2287.178 | −0.41 | |
| z | 22 | 2 | 1193.616 | 2386.225 | 2386.246 | −9.00 | |
| z | 22 | 3 | 796.087 | 2386.245 | 2386.246 | −0.39 | |
| z | 23 | 2 | 1244.166 | 2487.324 | 2487.294 | 12.15 | |
| z | 23 | 3 | 829.769 | 2487.292 | 2487.294 | −0.82 | |
| z | 24 | 2 | 1308.199 | 2615.391 | 2615.389 | 0.74 | |
| z | 24 | 3 | 872.467 | 2615.386 | 2615.389 | −1.12 | |
| z | 25 | 2 | 1386.752 | 2772.496 | 2772.498 | −0.71 | |
| z | 25 | 3 | 924.502 | 2771.490 | 2771.490 | 0.13 | |
| z | 26 | 2 | 1450.793 | 2900.580 | 2900.593 | −4.54 | |
| z | 26 | 3 | 967.198 | 2899.579 | 2899.585 | −1.88 | |
| z | 26 | 4 | 725.657 | 2899.608 | 2899.585 | 7.89 | |
| z | 27 | 2 | 1486.324 | 2971.641 | 2971.630 | 3.61 | |
| z | 27 | 3 | 991.214 | 2971.628 | 2971.630 | −0.55 | |
| z | 28 | 2 | 1554.848 | 3108.689 | 3108.689 | 0.20 | |
| z | 28 | 3 | 1036.566 | 3107.682 | 3107.681 | 0.44 | |
| z | 28 | 4 | 777.674 | 3107.674 | 3107.681 | −2.11 | |
| z | 29 | 2 | 1619.371 | 3237.734 | 3237.731 | 0.87 | |
| z | 29 | 3 | 1079.914 | 3237.726 | 3237.731 | −1.65 | |
| z | 29 | 4 | 809.937 | 3236.726 | 3236.724 | 0.83 | |
| z | 30 | 3 | 1113.603 | 3338.793 | 3338.779 | 4.27 | |
| z | 31 | 2 | 1751.432 | 3501.856 | 3501.842 | 3.89 | |
| z | 31 | 3 | 1167.617 | 3500.835 | 3500.835 | 0.13 | |
| z | 31 | 4 | 875.970 | 3500.857 | 3500.835 | 6.31 | |
| z | 32 | 2 | 1801.951 | 3602.894 | 3602.890 | 1.15 | |
| z | 32 | 3 | 1201.298 | 3601.878 | 3601.882 | −1.18 | |
| z | 32 | 4 | 901.222 | 3601.864 | 3601.882 | −5.00 | |
| z | 34 | 3 | 1258.339 | 3773.002 | 3772.996 | 1.69 | |
| z | 34 | 4 | 943.753 | 3771.989 | 3771.988 | 0.24 | |
| z | 35 | 2 | 1944.512 | 3888.016 | 3888.023 | −1.64 | |
| z | 35 | 3 | 1296.682 | 3888.032 | 3888.023 | 2.38 | |
| z | 35 | 4 | 972.505 | 3886.999 | 3887.015 | −3.94 | |
| z | 38 | 3 | 1419.430 | 4256.276 | 4256.276 | −0.08 | |
| z | 39 | 3 | 1457.453 | 4370.344 | 4370.319 | 5.64 | |
| z | 39 | 4 | 1093.334 | 4370.312 | 4370.319 | −1.60 | |
| z | 40 | 3 | 1500.466 | 4499.384 | 4499.362 | 4.93 | |
| z | 41 | 3 | 1538.157 | 4612.458 | 4612.446 | 2.59 | |
| z | 42 | 3 | 1587.176 | 4759.512 | 4759.514 | −0.39 | |
| z | 42 | 4 | 1190.382 | 4758.505 | 4758.506 | −0.19 | |
| z | 43 | 3 | 1619.871 | 4857.599 | 4857.575 | 5.01 | |
| z | 43 | 4 | 1215.402 | 4858.587 | 4858.583 | 1.01 | |
| z | 44 | 3 | 1663.225 | 4987.660 | 4987.685 | −5.02 | |
| z | 44 | 4 | 1247.428 | 4986.691 | 4986.677 | 2.65 | |
| z | 45 | 3 | 1700.923 | 5100.756 | 5100.769 | −2.67 | |
| z | 48 | 3 | 1804.996 | 5412.974 | 5412.960 | 2.60 | |
| Da | Da | ppm | |||||
| z | 48 | 4 | 1353.999 | 5412.975 | 5412.960 | 2.79 | |
| z | 49 | 3 | 1838.663 | 5513.973 | 5514.008 | −6.30 | |
| z | 50 | 3 | 1882.023 | 5644.054 | 5644.058 | −0.75 | |
| z | 50 | 4 | 1411.767 | 5644.046 | 5644.058 | −2.16 | |
| z | 51 | 3 | 1925.030 | 5773.075 | 5773.101 | −4.58 | |
| z | 51 | 4 | 1443.769 | 5772.053 | 5772.093 | −6.90 | |
| z | 52 | 3 | 1979.384 | 5936.137 | 5936.164 | −4.52 | |
| z | 56 | 4 | 1577.609 | 6307.416 | 6307.394 | 3.50 | |
| z | 57 | 4 | 1605.875 | 6420.479 | 6420.478 | 0.19 | |
| z | 58 | 4 | 1644.648 | 6575.571 | 6575.571 | −0.08 | |
| z | 61 | 4 | 1715.690 | 6859.738 | 6859.756 | −2.64 | |
| z | 62 | 4 | 1730.205 | 6917.799 | 6917.785 | 1.94 | |
| z | 63 | 4 | 1769.228 | 7073.888 | 7073.886 | 0.27 | |
| y | 9 | 1 | 927.468 | 927.468 | 927.468 | −0.32 | |
| y | 11 | 1 | 1211.627 | 1211.627 | 1211.628 | −0.83 | |
| y | 11 | 2 | 606.317 | 1211.626 | 1211.628 | −1.54 | |
| y | 12 | 2 | 670.365 | 1339.722 | 1339.723 | −0.87 | |
| y | 14 | 1 | 1524.853 | 1524.853 | 1524.852 | 0.72 | |
| y | 14 | 2 | 762.425 | 1523.843 | 1523.844 | −0.90 | |
| y | 31 | 3 | 1172.960 | 3516.865 | 3516.853 | 3.29 | |
| Unassigned | 2 | 622.864 | 1244.721 | ||||
| Unassigned | 2 | 499.310 | 997.612 | ||||
| Unassigned | 1 | 997.612 | 997.612 | ||||
| Unassigned | 2 | 563.339 | 1125.671 | ||||
| Unassigned | 1 | 527.821 | 527.821 | ||||
| Unassigned | 2 | 591.851 | 1182.694 | ||||
| Unassigned | 2 | 627.388 | 1253.769 | ||||
| Unassigned | 2 | 773.967 | 1546.926 | ||||
| Unassigned | 2 | 798.469 | 1595.931 | ||||
| Unassigned | 2 | 802.982 | 1604.956 | ||||
| Unassigned | 2 | 805.161 | 1609.314 | ||||
| Unassigned | 2 | 867.501 | 1733.994 | ||||
| Unassigned | 3 | 878.141 | 2632.410 | ||||
| Unassigned | 2 | 1563.359 | 3125.710 |