Table 3.
Differences in average mass of MH+ ions of active site peptides from intact or aged adducts of BChE with diEt-FAP or NEST with diBu-FAPa
BChE | NEST | |||
---|---|---|---|---|
Data Type | diEt-FAP intact | diEt-FAP aged | diBu-FAP intact | diBu-FAP aged |
Observed | 136.1 ± 0.1 (9) | 108.0 ± 0.1 (5) | 191.8 ± 0.2 (2) | 135.5 ± 0.1 (2) |
Theoretical | 136.1 | 108.0 | 192.2 | 136.1 |
Observed data are expressed as means ± SEM (n) of average masses (in Da). All observed values were statistically identical to their respective theoretical values (p > 0.05, one-sample t-test). Calculated mass shifts take into account the mass of the serine hydroxyl proton lost in the organophosphorylation reaction and assume that the aged species is protonated because of the acidic conditions used for MS [29]. Intact adducts are dialkylphosphoryl; aged adducts are monoalkylphosphoryl.