Mass spectra of TaF, TaX, and TaY activity. (A–E) Broad band mass spectra of Ta1-T8 (+8 charge state) displaying holo-Ta1-T8 (blue), Acac-S-Ta1-T8 (red), γ-methyl-HMG-S-Ta1-T8 (green), dehydrated γ-methyl-HMG-S-Ta1-T8 (orange), and isohexenyl-S-Ta1-T8 (purple). (A) Acac-S-Ta1-T8 + PropTaE + TaF incubated for 20 minutes. (B) Acac-S-Ta1-T8 + PropTaE incubated for 20 minutes. (C) Acac-S-Ta1-T8 + PropTaE + TaF + TaY incubated for 35 minutes. (D) Acac-S-Ta1-T8 + PropTaE + TaF + TaX incubated for 35 minutes. (E) Acac-S-Ta1-T8 + PropTaE + TaF + TaX + TaY incubated for 35 minutes. (F–J) Mass spectra of the +1 charge state phosphopantatheinyl elimination product ions from A–E, respectively. (Right) Structures of phosphopantetheinyl elimination fragment ions and their respective masses.