Table 2.
Tandem mass spectrometry fragment assignments for MC-LR (1) and 3–6 observed by electrospray ionization collision-induced dissociation.
| Fragment Assignment a | MC-LR b (1) | [Gly1, Asp3, Dhb7] MC-LR (3) | [Gly1, Asp3, Dhb7] MC-LHar (4) | [Gly1, Asp3, ADMAdda5, Dhb7] MC-LR (5) | [Gly1, Asp3, ADMAdda5, Dhb7] MC-LHar (6) |
|---|---|---|---|---|---|
| M + H | 995.6 | 967.6 | 981.6 | 995.6 | 1,009.6 |
| M − HOAc + H | - | - | - | 935.5 | 949.3 |
| (Me)Asp-Arg/Har-(ADM)Adda-Glu-Mdha/Dhb-Gly/Ala + H | 882 | 868.6 | 896.9 | ||
| Arg/Har-(ADM)Adda-Glu-Mdha/Dhb-Gly/Ala + H | 753 | 753.3 | 781.4 | ||
| (Me)Asp-Arg/Har-(ADM)Adda-Glu + H | 728 | 728.4 | 756.4 | ||
| Arg/Har-(ADM)Adda-Glu-Mdha/Dhb + H | 682 | 682.5 | 696.1 | 710.3 | 724.3 |
| Glu-Mdha/Dhb-Gly/Ala-Leu-(Me)Asp-Arg/Har + H | 682 | 668.0 | |||
| Arg/Har-(ADM)Adda-Glu + H | 599 | 599.3 | 613.2 | 627.2 | 641.4 |
| (Me)Asp-Arg/Har-(ADM)Adda + H | 599 | 627.3 | |||
| (ADM)Adda’-Glu-Mdha/Dhb-Gly/Ala-Leu + H | 559 | 545.4 | |||
| Mdha/Dhb-Gly/Ala-Leu-(Me)Asp-Arg/Har + H | 553 | 525.2 | 539.4 | 525.2 | 539.3 |
| Glu-Mdha/Dhb-Gly/Ala-Leu-(Me)Asp + H | 526 | 498.2 | |||
| Arg/Har-(ADM)Adda + H | 470 | 512.3 | |||
| Gly/Ala-Leu-(Me)Asp-Arg/Har + H | 470 | 442.3 | 456.2 | 442.1 | 456.1 |
| (ADM)Adda’-Glu-Mdha/Dhb-Gly/Ala + H | 446 | 432.2 | 432.1 | ||
| Leu-(Me)Asp-Arg/Har + H | 399 | 385.1 | 399.1 | 385.4 | |
| Glu-Mdha/Dhb-Gly/Ala-Leu + H | 397 | 383.1 | 383.1 | ||
| (ADM)Adda'-Glu-Mdha/Dhb + H | 375 | 375.1 | 375.2 | 375.2 | |
| Mdha/Dhb-Gly/Ala-Leu-(Me)Asp + H | 397 | 369.2 | |||
| (ADM)Adda'-Glu + H | 292 | 292.1 | 292.2 | 292.1 | 292.1 |
| Gly/Ala-Leu-(Me)Asp + H | 314 | 286.1 | 286.3 | 286.1 | |
| ADMAdda − HOAc + H | - | - | - | 282.2 | 282.2 |
| ADMAdda − HOAc − NH3 + H | - | - | - | 265.1 | 265.2 |
| (Me)Asp-Arg/Har + H | 286 | 272.1 | 286.1 | 272.1 | 286.1 |
| Glu-Mdha/Dhb-Gly/Ala + H | 284 | 270.2 | 270.2 | 270.1 | 270.2 |
| Mdha/Dhb-Gly/Ala-Leu + H | 268 | 254.3 | 254.1 | 254.1 | 254.1 |
| Leu-(Me)Asp + H | 243 | 229.2 | 229.0 | 229.1 | |
| Glu-Mdha/Dhb + H | 213 | 213.1 | 213.1 | 213.1 | 213.1 |
| Gly/Ala-Leu + H | 185 | 171.0 | 171.1 | 171.0 | 171.1 |
| (ADM)Adda' + H | 163 | 163.1 | 163.1 | 163.1 | 163.0 |
| Arg/Har + H | 157 | 157.0 | 171.1 | 157.1 | 171.1 |
| Mdha/Dhb-Gly/Ala + H | 155 | 141.0 | 141.0 | 141.1 | 141.1 |
| (ADM)Adda sidechain | 135 | 135.1 | 135.1 | 163.1 | 163.0 |
| Arg/Har immonium | 129 | 129.2 | 143.1 | 129.1 | 143.1 |
| Arg/Har fragment | 112 | 112.1 | 112.0/126.1 | 112.0 | 111.9/126.1 |