Table 1.
MALDI-MS peak assignments to most abundant HDL apolipoproteins and their combinations
| Apolipoprotein Combinations | Calculated Mr (kDa)a | Predicted MALDI-MS (kDa)b | Presence in MALDI-MSc | Clarity by MALDI-MS | Clarity by MALDI- MS and PAGE |
|---|---|---|---|---|---|
| 1A-I | 28.1 | 30.3d | YES (30.3) | YES | YES |
| 1A-I+1C-III | 36.9 | 39.8 | NO | N/A | N/A |
| 1A-I+1A-II | 45.5 | 49.1 | YES (49.1) | YES | YES |
| 2A-I | 56.2 | 60.6 | YES (60.6) | YES | YES |
| 1A-I+2A-II | 62.9 | 67.9 | NO | N/A | N/A |
| 2A-I+1C-III | 65.0 | 70.2 | YES (70.4) | NO | PARTIAL |
| Albumin | 66.4 | 71.7 | YES (70.4) | NO | PARTIAL |
| 2A-I+1A-II | 73.6 | 79.5 | YES (78.9) | NO | PARTIAL |
| 2A-I+2C-III | 73.6 | 79.5 | YES (78.3) | NO | PARTIAL |
| 2A-I+1A-II+1C-III | 82.4 | 88.9 | YES (88.7) | YES | YES |
| 3A-I | 84.3 | 91.1 | YES (91.1) | YES | YES |
| 2A-I+2A-II | 91.0 | 98.3 | YES (97.8) | YES | YES |
| 3A-I+1C-III | 93.0 | 100.5 | YES (98.9) | YES | YES |
| 2A-I+2A-II+1C-III | 99.8 | 107.8 | YES (105.6) | YES | YES |
| 3A-I+1A-II | 101.7 | 109.9 | NO | N/A | N/A |
| 3A-I+2C-III | 101.7 | 109.9 | NO | N/A | N/A |
| 2A-I+3A-II | 108.4 | 117.4 | YES (117.6) | YES | YES |
| 4A-I | 112.4 | 121.5 | YES (121.1) | YES | YES |
| 3A-I+2A-II | 119.1 | 128.7 | NO | N/A | N/A |
| 4A-I+1C-III | 121.15 | 130.9 | YES (129.5) | YES | YES |
| 5A-I | 140.5 | 151.9 | NO | N/A | N/A |
| 4A-I+1A-II | 147.2 | 159.1 | NO | N/A | N/A |
Masses of apolipoprotein combinations were calculated by addition of theoretical Mr of corresponding apolipoproteins.
Predicted MALDI-MS peak locations for cross-linked apolipoproteins in LpA-I and LpA-I/A-II subfractions were estimated based on the linear regression obtained for lipid free apoA-I measurements (Figure 7). A linear regression was generated between theoretical masses calculated for apoA-I monomer, dimer, trimer, tetramer and observed MALDI-MS masses for optimally cross-linked apoA-I oligomers, which resulted in a 0.99 correlation coefficient.
Presence of the predicted masses in MALDI-MS spectra are listed as “YES” or “NO” along with the values observed for masses in parenthesis.
Predicted masses for the rows highlighted in grey were directly taken from the cross-linked apoA-I oligomer measurements in Figure 7.