Table 1. Gluten peptides containing cysteine, S-carbamidomethyl cysteine, or S-β-(4-pyridylethyl) cysteine, detected by LC-MS/MS after chymotryptic digestion of a reduced/unalkylated or reduced/alkylated protein extract of wheat flour (cv. Akteur).
Reduction | Alkylation with iodoacetamide | Alkylation with 4-vinylpyridine | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Amino acid sequence | Mr | M/z | Score | RT (min) | Mr | M/z | Score | RT (min) | Mr | M/z | Score | RT (min) |
ALETLPAMCNVY | 1380.6 | 691.3 | 24 | 55.1 | 1428.7 | 715.4 | 19 | 50.1 | ||||
CCQQL | 707.3 | 708.2 | 44 | 18.4 | ||||||||
CCQQLL | 820.4 | 821.3 | 68 | 33.9 | ||||||||
CCQQLW | 893.4 | 894.3 | 63 | 41.3 | ||||||||
CNVY | 602.3 | 603.3 | 17 | 16.9 | ||||||||
CSTTIAPF | 895.4 | 896.4 | 19 | 45.1 | ||||||||
CSVNVPL | 835.4 | 836.3 | 30 | 36.0 | ||||||||
CTIAPF | 707.3 | 708.3 | 34 | 44.6 | 755.4 | 756.3 | 35 | 37.9 | ||||
CTIAPVGF | 863.4 | 864.4 | 59 | 48.6 | 911.5 | 456.8 | 78 | 42.5 | ||||
CTIAPVGIF | 976.5 | 977.5 | 47 | 58.9 | 1024.5 | 513.3 | 34 | 51.6 | ||||
ELEACQQVVDQQL | 1606.8 | 804.3 | 15 | 23.1 | ||||||||
GQCSF | 597.2 | 598.2 | 25 | 20.9 | ||||||||
GQCVSQPQQQL | 1271.6 | 636.8 | 40 | 28.4 | 1319.6 | 660.9 | 20 | 25.6 | ||||
GQCVSQPQQQSQQQL | 1742.8 | 872.4 | 53 | 27.4 | ||||||||
IPCMDVVL | 993.5 | 497.9 | 20 | 51.3 | ||||||||
IPEQSRCQAIH | 1280.6 | 641.4 | 17 | 22.2 | ||||||||
LGECCSRL | 993.4 | 497.7 | 68 | 25.9 | ||||||||
LLQQCNPVSL | 1218.6 | 610.4 | 22 | 41.7 | ||||||||
LQQCNPVSL | 1057.5 | 529.7 | 44 | 39.1 | 1105.6 | 553.9 | 42 | 35.2 | ||||
LQQQCIPVAM | 1234.6 | 618.3 | 16 | 40.6 | ||||||||
NPCKNFL | 891.4 | 446.8 | 24 | 17.6 | ||||||||
QCEREL | 833.4 | 417.7 | 39 | 15.9 | ||||||||
QCERELQEL | 1203.6 | 602.7 | 136 | 32.4 | ||||||||
QQCNPVSL | 944.4 | 945.4 | 46 | 34.7 | ||||||||
QQLNPCKL | 942.5 | 943.4 | 15 | 38.4 | ||||||||
QQQLIPCMDVVL | 1442.7 | 722.4 | 30 | 66.7 | 1490.8 | 746.4 | 16 | 60.4 | ||||
QQQLNPCKNIL | 1354.7 | 678.4 | 28 | 29.2 | ||||||||
SQQQPCSQQQQQPL | 1683.8 | 842.9 | 534 | 25.4 | 1731.8 | 578.4 | 71 | 23.4 | ||||
SQVCF | 639.3 | 640.2 | 23 | 32.1 | ||||||||
VPPDCSTINVPY | 1360.6 | 681.3 | 22 | 46.5 | ||||||||
VPPECSIM | 979.5 | 490.8 | 25 | 34.5 | ||||||||
WQSSCH | 803.3 | 804.3 | 17 | 43.2 | ||||||||
YPSVTCPQQVSY | 1370.6 | 686.3 | 20 | 45.3 | 1427.6 | 714.9 | 47 | 41.9 | 1475.7 | 738.8 | 42 | 38.8 |