Table 1.

Analysis of [redox-¹³C] labeled peptone. LC-ESI-MS/MS results (left) are compared with NMR results (right) and the labeling pattern expected from typical anabolic pathways. “++” indicates the most intense peak in the MS/MS spectra. Lower case letters in the atom labels indicate expectation of lighter labeling because symmetric carbons of 3-dehydroquinate can arise equally from labeled and unlabeled carbons of erythrose 4-phosphate in the shikimate pathway.

Amino acid (MS)/fragment (MS2)	Control M/Z	Labeled Mass Increment					Labels expected	COSY result
		+0	+1	+2	+3	+4
Ala	90	+	++				C
– HCOOH	44	++
Arg	175		+	++	+		C, CD, CZ
– NH3	158		+	++	+		C,CD,CZ
– COOH	130	−	++	+			CD,CZ
– (NH)C(NH2)2	116	−	+	++			C,CD
– HCOOH, (NH)C(NH2)2	70		++				CD	80%
C(NH2)3	60	+	+				CZ
Asp	134		++	+			C,CG
– H2O	116	−	++	+			C,CG
– HCOOH	88	+	++				CG
Cys							C
Gly							C
Glu	148		+	++			C,CD
– H2O	130		+	++			C,CD
– HCOOH	102	−	++				CD
– HCOOH, H2O	84		++				CD
His	156	+	++	+			CB,CG,CD2
Ile	132	−	++	+			C,CD
– HCOOH	86	+	++				CD	62%
Leu	132		++	−			C
– HCOOH	86	++	−				---
Lys	147	+	++	+			C,CG
– NH3	130	+	++	+			C,CG
– NH3, HCOOH	84	+	++				CG	~60%
Met	150	−	++	+			C,CG
– NH3	133	−	++	+			C,CG
– HCOOH	104	+	+				CG	63%
Phe	166	+	+	++	+		C,CZ,Ce1,Ce2
– HCOOH	120	+	++	+			CZ,Ce1,Ce2
Pro	116		+	++			C,CD
– HCOOH	70	−	++	−			CD	~99%
Ser	106	+	++				C
– H2O	88	+	++				C
– HCOOH	60	++					---
Thr	120	−	++	+			C,CG
– H2O	102	−	++	+			C,CG
– H2O, H2O	84	−	++	+			C,CG
– HCOOH	74	+	++				CG	67%
– HCOOH, H2O	56		++				CG	67%
Trp	205	+	+	+	++	+	C,CG,CD1,CH2, Cz2,Cz3
Tyr	182	+	+	++	+		C,CZ,Ce1,Ce2
– NH3	165	+	+	++	+		C,CZ,Ce1,Ce2
– H2O, H2O	146	−	−	++	+	−	C,CZ,Ce1,Ce2
– HCOOH	136	+	++	+			CZ,Ce1,Ce2
Val	118	+	++				C
– HCOOH	72	++					---