BioMed Research International

Methodology Report

Enhanced MALDI-TOF MS Analysis of Phosphopeptides Using an Optimized DHAP/DAHC Matrix

Table 1

The peptides investigated in this study ∗ .
Peptide IDSequence No.Sequence [ M + H ] + T h e o B+B
T 𝛼 1aa 106–119VPQLEIVPNpSAEER1660.79260
T 𝛼 2aa 104 –119KYKVPQLEIVPNpSAEER1951.95 − 710
T 𝛼 3aa 43–58DIGpSEpSTEDQAMEDIK1927.683960
T 𝛼 4aa 59–79QMEAEpSIpSpSpSEEIVPNpSVEQK2720.903680
T 𝛼 5aa 37–58VNELpSKDIGpSEpSTEDQAMEDIK2678.023840
T 𝛼 6aa 138–149TVDMEpSTEVFTK1466.60 − 210
T 𝛼 7aa 46–70NANEEEYSIGpSpSpSEEpSAEVATEEVK3008.027100
T 𝛼 8aa 1–21KNTMEHVpSpSpSEESIIpSQETYK2747.002810
T 𝛼 9aa 2–21NTMEHVpSpSpSEESIIpSQETYK2618.912350
T 𝛽 1aa 33 –48FQpSEEQQQTEDELQDK2061.826200
T 𝛽 2aa 1–25RELEELNVPGEIVEpSLpSpSpSEESITR3122.26 − 220
T10aa 81–91ALNEINQFYQK1367.70 − 750
T4aa 23–34FFVAPFPEVFGK1384.73 − 5530
T3aa 8–22HQGLPQEVLNENLLR1759.59 − 590
T11aa 91–100YLGYLEQLLR1267.71 − 6480
T18aa 132–150EPMIGVNQELAYFYPELFR2316.14 − 6900
pT—VNQIGpTLSESIK1368.44 − 310
pY—SGSLHRIpYTHQS1465.482300
∗ Phosphopeptides in tryptic digest of 𝛽 casein and 𝛼 casein are denoted as T 𝛽 1~2 and T 𝛼 1~9, respectively. The sites of phosphorylation are indicated with the letter “p” in the listed peptide sequences. T3, T4, T11, and T18 are nonphosphorylated peptide from 𝛼 casein S1. T10 is a nonphosphorylated peptide from 𝛼 -casein S2. pT and pY are the synthesized standard phosphopeptides. [M+H] + denotes the theoretical monoisotopic m/z mass. “B+B” means Bull and Breese Index for peptides calculated by the Masslynx software (Waters/Micromass).