Table 1.
β-Lactoglobulin (bovine) CAD/ECD product ions with disulfide bond cleavages.
| Ion Assignment | Observed Mass (Da) | Theoretical Mass (Da) | Mass Error (Da) | Mass Error (ppm) | Note |
|---|---|---|---|---|---|
| b69 | 7596.894 | 7596.924 | −0.030 | −3.9 | Cys66+H; one disulfide cleavage |
| b111 | 12471.391 | 12471.473 | −0.083 | −6.6 | Cys66+SH; Cys106+SH; two disulfide cleavage |
| b133 | 14829.601 | 14829.607 | −0.007 | −0.5 | Cys66−H; one disulfide cleavage |
| b134 | 14961.686 | 14961.673 | 0.013 | 0.8 | Cys66+H; one disulfide cleavage |
| b*134 | 14976.677 | 14976.618 | 0.059 | 3.9 | Cys66+SH; one disulfide cleavage |
| b∘138 | 15493.926 | 15493.920 | 0.006 | 0.4 | Cys66+SH; one disulfide cleavage |
| b∘∘138 | 15475.945 | 15475.885 | 0.059 | 3.8 | Cys66+SH; one disulfide cleavage |
| y4 | 498.217 | 498.213 | 0.007 | 8.1 | Cys160−H; one disulfide cleavage |
| y5 | 660.276 | 660.271 | 0.012 | 7.3 | Cys160+S; one disulfide cleavage |
| y6 | 789.319 | 789.314 | 0.008 | 6.6 | Cys160+S; one disulfide cleavage |
| y21 | 2476.256 | 2476.235 | 0.037 | 8.5 | Cys160−H; one disulfide cleavage |
| y22 | 2571.371 | 2571.350 | 0.051 | 8.2 | Cys160−SH; one disulfide cleavage |
| y23 | 2749.395 | 2749.422 | −0.053 | −9.7 | Cys160+S; one disulfide cleavage |
| y25 | 2949.497 | 2949.526 | −0.040 | −9.8 | Cys160+SH; one disulfide cleavage |
| y*25 | 2931.475 | 2931.492 | −0.017 | −5.8 | Cys160+S; one disulfide cleavage |
| y28 | 3305.749 | 3305.729 | 0.021 | 6.2 | Cys160−H; one disulfide cleavage |
| c69 | 7614.951 | 7614.958 | −0.006 | −0.8 | Cys66+H, one disulfide bond cleavage |
| c76 | 8398.440 | 8398.443 | −0.003 | −0.3 | Cys66+H, one disulfide bond cleavage |
| c82 | 9053.842 | 9053.849 | −0.006 | −0.7 | Cys66+H, one disulfide bond cleavage |
| c84 | 9295.026 | 9295.028 | −0.002 | −0.2 | Cys66+H, one disulfide bond cleavage |
| c114 | 12712.642 | 12712.726 | −0.084 | −6.6 | Cys66−SH, Cys106−SH, two disulfide bond cleavage |
| c124 | 13912.071 | 13912.200 | −0.129 | −9.3 | Cys66+SH, one disulfide bond cleavage |
| z6 | 741.287 | 741.287 | 0.0001 | 0.1 | Cys160−H, one disulfide cleavage |
| z7 | 854.371 | 854.371 | −0.0004 | −0.5 | Cys160−H, one disulfide cleavage |
| z8 | 982.429 | 982.430 | −0.0005 | −0.5 | Cys160+H, one disulfide cleavage |
| z•11 | 1296.591 | 1296.589 | 0.002 | 1.6 | Cys160−H, one disulfide cleavage, mass off |
| z17 | 2047.010 | 2046.994 | 0.016 | 8.0 | Cys160+SH, one disulfide bond cleavage |
| z•22 | 2622.319 | 2622.299 | 0.020 | 7.5 | Cys160−SH, one disulfide cleavage |
| z31 | 3602.850 | 3602.874 | −0.023 | −6.5 | Cys160−H, one disulfide cleavage |
| z•26 | 3017.541 | 3017.570 | −0.029 | −9.6 | Cys160−H, one disulfide cleavage |
| z29 | 3418.785 | 3418.752 | 0.082 | 9.5 | Cys160+H, one disulfide cleavage |
| z39 | 4546.339 | 4546.298 | 0.050 | 9.0 | Cys160+H, one disulfide cleavage |
*
denotes ammonium neutral loss;
∘ and ∘∘
denote one and two water loss ions, respectively.