TABLE 3.
List of apoB-100-derived tryptic peptides carrying modifications generated by the MPO-H2O2-Cl− system under drastic conditions (molar ratio = 625:1)
| Peptide | Error (ppm) | Peptide Score | % SPI | Z | Sequence with Fragmentation | Modified Amino Acid |
| 102–105 | 1.9 | 3.1 | 80 | 2 | (R)y/E/L K(L) | Cl-Tyr102 |
| 748–751 | 3.7 | 3.0 | 84 | 2 | (R)A/y/L R(I) | Cl-Tyr749 |
| 1,108–1,118 | −0.5 | 15.0 | 76 | 2 | (R)S/E|I|L|A|H|w/S|P A K(L) | OxTrp1114 |
| 1,108–1,118 | −0.6 | 12.0 | 81 | 2 | (R)S E|I|L|A/H w|S/P A K(L) | di-OxTrp1114 |
| 1,176–1,183 | 3.2 | 12.6 | 87 | 3 | (K)S/L/H/m y|A/N/R(L) | O-Met1179 HO-Tyr1180 |
| 1,573–1,583 | 1.0 | 14.1 | 71 | 2 | (R)S E|y|Q|A|D/Y/E/S L/R(F) | Cl-Tyr1575 |
| 1,682–1,694 | 0.1 | 10.8 | 63 | 2 | (L)S L|G S\A|y Q A m I/L/G/V/D/S K(N) | O-Met1690 Cl-Tyr1687 |
| 1,743–1,750 | 2.3 | 6.3 | 82 | 2 | (K)L D/N\I/y/S S D K F Y/K(Q) | Cl-Tyr1747 |
| 1,890–1,901 | 0.4 | 10.2 | 71 | 2 | (K)L A|L/w|G E H T G Q|L\Y(S) | OxTrp1893 |
| 1,890–1,901 | 0.9 | 13.5 | 79 | 2 | (K)L A|L|w|G E H T G Q|L|Y(S) | di-OxTrp1893 |
| 1,941–1,955 | −0.5 | 10.4 | 70 | 3 | (K)V S A L L|T|P A E Q T/G T w K(L) | OxTrp1954 |
| 1,941–1,955 | 1.8 | 13.4 | 80 | 2 | (K)V S A|L|L|T|P A E/Q T G T w/K(L) | di-OxTrp1954 |
| 2,086–2,106 | 1.7 | 18.2 | 94 | 3 | (R)A A|L|G K\L|P Q Q A N D\Y|L|N/S/F/N w/E R(Q) | di-OxTrp2104 |
| 2,214–2,228 | −2.9 | 15.8 | 74 | 2 | (K)S G S S T/A/S/w|I|Q/N/V|D/T/K(Y) | di-OxTrp2221 |
| 2,334–2,341 | 1.8 | 11.9 | 73 | 2 | (K)L/V|E/L/A/H Q y(K) | Cl-Tyr2341 |
| 2,402–2,415 | −0.7 | 5.1 | 64 | 3 | (K)S F|D/y H Q F V/D E T N D K(I) | Cl-Tyr2405 |
| 2,462–2,478 | 0.3 | 8.5 | 74 | 2 | (K)I T L\I I\N w\L Q E\A\L|S\S A/S L(A) | OxTrp2468 |
| 2,462–2,478 | −1.6 | 10.8 | 83 | 2 | (K)I T L\I\I N w\L\Q E\A\L|S|S A/S L(A) | di-OxTrp2468 |
| 2,496–2,507 | 0.7 | 12.0 | 80 | 2 | (R)m y/Q/m D I|Q/Q/E L/Q/R(Y) | O-Met2496, 2499 HO-Tyr2497 |
| 2,542–2,548 | 2.0 | 12.5 | 77 | 2 | (Y)S/I|Q/D/w/A/K(R) | OxTrp2546 |
| 2,533–2,548 | −0.1 | 15.0 | 70 | 2 | (K)N L\T D|F/A/E|Q/Y/S I/Q/D w/A/K(R) | di-OxTrp2546 |
| 2,731–2,736 | 2.0 | 6.2 | 73 | 2 | (K)L/y/S I/L/K(I) | Cl-Tyr2732 |
| 2,889–2,899 | 3.6 | 11.0 | 73 | 3 | (K)A G H\I A\w|T S/S/G/K(G) | di-OxTrp2894 |
| 3,051–3,065 | 0.1 | 17.9 | 80 | 2 | (F)L/S/P S A/Q/Q|A|S w/Q/V/S A/R(F) | OxTrp3060 |
| 3,051–3,065 | 1.3 | 13.9 | 73 | 2 | (F)L/S/P S A/Q|Q/A/S/w/Q V/S A R(F) | di-OxTrp3060 |
| 3,122–3,128 | 2.0 | 10.7 | 73 | 2 | (K)D F|S L/w/E K(T) | di-OxTrp3126 |
| 3,511–3,520 | 0.9 | 16.2 | 85 | 2 | (K)I/D|D|I|w/N L/E/V/K(E) | OxTrp3515 |
| 3,511–3,520 | 1.5 | 16.2 | 84 | 2 | (K)I/D|D|I|w|N L/E/V/K(E) | di-OxTrp3515 |
| 3,532–3,541 | 0.3 | 16.9 | 77 | 2 | (R)I/Y|S|L/w/E/H|S T/K(N) | OxTrp3536 |
| 3,532–3,541 | 1.7 | 13.6 | 83 | 3 | (R)I/Y/S L/w|E H/S T K(N) | di-OxTrp3536 |
| 3,604–3,611 | 1.7 | 4.5 | 68 | 3 | (K)I R w|K/N E/V R(I) | di-OxTrp3606 |
| 3,647–3,655 | −4.4 | 5.0 | 78 | 2 | (K)N I|I/L/P V y D K(S) | Cl-Tyr3653 |
| 3,656–3,662 | 1.3 | 6.8 | 78 | 2 | (K)S L|w/D F L K(L) | OxTrp3658 |
| 3,656–3,662 | 7.5 | 10.3 | 72 | 2 | (K)S/L|w/D/F L/K(L) | di-OxTrp3658 |
| 3,860–3,876 | 0.1 | 18.3 | 85 | 3 | (R)F E\V D S\P\V|Y/n/A/T/w/S A/S L K(N) | OxTrp3871 |
| 3,860–3,876 | 0.7 | 17.2 | 80 | 2 | (R)F E|V|D/S|P V/Y/n/A T w/S A/S L K(N) | di-OxTrp3871 |
| 3,926–3,946 | −0.4 | 14.2 | 70 | 3 | (R)D F|S|A/E|Y|E E D G K Y E/G L/Q E w E G K(A) | di-OxTrp3943 |
| 4,106–4,120 | 1.4 | 10.6 | 69 | 3 | (K)A/A|S/G/T/T/G T y Q E W K D K(A) | HO-Tyr4114 |
| 4,106–4,120 | −0.1 | 11.2 | 64 | 3 | (K)A/A|S/G/T/T/G T Y Q E w/K D K(A) | di-OxTrp4117 |
| 4,235–4,243 | 0.2 | 10.5 | 87 | 2 | (K)L I|D|V|I|S/m y R(E) | O-Met4241 Cl-Tyr4242 |
| 4,359–4,372 | 1.2 | 15.3 | 74 | 2 | (R)E E Y|F/D|P S I|V/G w/T V/K(Y) | di-OxTrp4369 |
LDL was modified by HOCl generated by the MPO-H2O2-Cl− system using drastic conditions (oxidant/LDL molar ratio = 625:1 considering equimolar formation of HOCl). ApoB-100 mapping was carried out by RRLC-MS/MS, and listed modifications are the ones not recovered with the softest conditions described in Table 1 and Table 2. Each modified peptide is characterized by its peptide score, % SPI, mass error, fragmentation, and position(s) of modified residue(s).