Table 4.
Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF–MS)-positive ion spectrum of Eprex®, Binocrit®, and Retacrit® after trypsin digestion compared with in silico analysis (MH+ calculated)
| Peptide | Sequence | MH+ (m/z)a calculatedb | MH+ (m/z)a observed | ||
|---|---|---|---|---|---|
| EPR | BIN | RET | |||
| 28–31 | APPR | 440.2616 | 440.2793 | 440.2691 | 440.2606 |
| 32–37 | LICDSR (Cys_CAM: 34) | 763.3767 | 763.4197 | 763.4238 | 763.4025 |
| 38–41 | VLER | 516.314 | 516.343 | 516.3317 | 516.3189 |
| 42–47 | YLLEAK | 736.4239 | 736.4591 | 736.4719 | 736.4506 |
| 48–72 | EAENITTGCAEHCSLNENITVPDTK (Cys_CAM: 56, 60) | 2803.2509c | nd | nd | nd |
| 73–79 | VNFYAWK | 927.4723 | 927.517 | 927.5312 | 927.5057 |
| 73–80 | VNFYAWKR (1 missed cleavage) | 1083.5734 | 1083.556 | 1083.5669 | 1083.5288 |
| 80–103 | RMEVGQQAVEVWQGLALLSEAVLR (1 missed cleavage) | 2683 | 2682.544 | 2682.5193 | 2682.4392 |
| 81–103 | MEVGQQAVEVWQGLALLSEAVLR | 2526.3384 | 2526.431 | 2526.4316 | 2526.3394 |
| 104–124 | GQALLVNSSQPWEPLQLHVDK | 2359.2404d | nd | nd | nd |
| 125–130 | AVSGLR | 602.362 | 602.3907 | 602.3914 | 602.377 |
| 125–137 | AVSGLRSLTTLLR (1 missed cleavage) | 1386.8427 | 1387.936 | 1387.9481 | 1387.8857 |
| 131–137 | SLTTLLR | 803.4985 | 803.5432 | 803.5517 | 803.5271 |
| 144–158 | EAISPPDAASAAPLR | 1465.7645 | 1465.838 | 1465.8389 | 1465.8013 |
| 144–158 | EAISPPDAASAAPLR + GalNAc + Galattosio | 1830.9526 | 1830.978 | 1830.9824 | 1830.9257 |
| 159–166 | TITADTFR | 924.4785 | 924.5321 | 924.5418 | 924.5117 |
| 178–180 | LFR | 435.2714 | 435.2868 | 435.2772 | 435.2696 |
| 171–181 | VYSNFLRGKLK (2 missed cleavage) | 1324.7735 | 1324.736 | 1324.7417 | 1324.6876 |
| 171–177 | VYSNFLR | 898.4781 | 898.5297 | 898.5392 | 898.5113 |
| 178–181 | GKLK (1 missed cleavage) | 445.3133 | 445.0568 | 445.0473 | 445.0364 |
| 182–189 | LYTGEACR (Cys_CAM: 188) | 969.4458 | 969.4949 | 969.5083 | 969.4836 |
BIN Binocrit®, EPR Eprex®, nd not detected, PNGase F peptide-N4-(acetyl-b-glucosaminyl)-asparagine amidase F, RET Retacrit®
aAll values are monoisotopic masses
bTheoretical protonated molecule ions of peptides based on peptide mass [33]
cPlus 2 Da after peptide-N4-(acetyl-b-glucosaminyl)-asparagine amidase-catalyzed deglycosylation [34, 35]
dPlus 1 Da after peptide-N4-(acetyl-b-glucosaminyl)-asparagine amidase-catalyzed deglycosylation [34, 35]