LC-MS analysis of the α-ketoglutarate (24) PFBHA oxime generated from glutamate (17) in the AFMN synthase-catalyzed reaction (negative mode). Left, EIC at m/z 340.0244 for the PFBHA trapped α-ketoglutarate (red trace, trapped α-KG formed in the enzymatic reaction; blue trace, trapped α-KG standard; and green trace, co-elution of trapped α-KG standard and same formed in the AFMN synthase-catalyzed reaction. Right, ESI-MS of the 340.0244 Da species consistent with the α-ketoglutarate PFBHA oxime.