. 2014 Jul;80(14):4234–4241. doi: 10.1128/AEM.00740-14

TABLE 2.

Selected examples for biomarker peptides which are discriminative for all three investigated subspecies^a

Salmonella subspecies	Assigned protein	Protein mass (kDa)	Biomarker peptide mass (Da)	Amino acid exchange(s) (subspecies)^c
S. arizonae	6-Phosphogluconolactonase	36.4	3,004.52 ± 0.03^b	A→C, Y→H, A→V (S. enterica)
S. arizonae	6-Phosphogluconolactonase	36.4	3,004.52 ± 0.03^b	A→C, Y→H, A→V, E→A (S. houtenae)
S. arizonae	Arsenate reductase	13.4	1,420.81 ± 0.00	E→D (S. enterica*)
S. arizonae	Arsenate reductase	13.4	1,420.81 ± 0.00	E→D, G→S (S. houtenae*)
S. arizonae	Ferric uptake regulator	17.0	3,291.42 ± 0.01	Q→H (S. enterica)
S. arizonae	Ferric uptake regulator	17.0	3,291.42 ± 0.01	E→D, Q→H (S. houtenae)
S. arizonae	Membrane protein	15.7	3,051.48 ± 0.02^b	L→I, T→A (S. enterica*)
S. arizonae	Membrane protein	15.7	3,051.48 ± 0.02^b	L→I, M→V, T→A (S. houtenae*)
S. arizonae	N-Ethylmaleimide reductase	39.5	2,590.17 ± 0.02	K→E, E→A (S. enterica*)
S. arizonae	N-Ethylmaleimide reductase	39.5	2,590.17 ± 0.02	E→A (S. houtenae*)
S. arizonae	NADH dehydrogenase subunit G	100.0	3,009.44 ± 0.01^b	H→Q (S. enterica)
S. arizonae	NADH dehydrogenase subunit G	100.0	3,009.44 ± 0.01^b	A→T, D→G, H→Q (S. houtenae)
S. enterica	Cell division protein DamX	45.5	3,153.62 ± 0.03^b	TT→AP, TA→KV (S. arizonae•)
S. enterica	Cell division protein DamX	45.5	3,153.62 ± 0.03^b	A→T, T→K, A→T (S. houtenae)
S. enterica	Fumarate hydratase	51.8	2,460.30 ± 0.01^b	P→S (S. arizonae)
S. enterica	Fumarate hydratase	51.8	2,460.30 ± 0.01^b	L→M (S. houtenae*)
S. enterica	H-NS histone family	15.5	1,979.88 ± 0.01	MD→IN (S. arizonae*)
S. enterica	H-NS histone family	15.5	1,979.88 ± 0.01	D→G (S. houtenae*)
S. enterica	Peptidyl-prolyl cis-trans-isomerase PpiD	58.2	2,187.04 ± 0.00	V→A, V→T (S. arizonae*)
S. enterica	Peptidyl-prolyl cis-trans-isomerase PpiD	58.2	2,187.04 ± 0.00	V→T (S. houtenae*)
S. enterica	Probable thiol peroxidase	18.0	2,379.23 ± 0.01	S→N (S. arizonae*)
S. enterica	Probable thiol peroxidase	18.0	2,379.23 ± 0.01	T→A (S. houtenae*)
S. enterica	Putative outer membrane protein	12.8	3,224.54 ± 0.02^b	L→F, S→R, S→I, N→Y (S. arizonae•)
S. enterica	Putative outer membrane protein	12.8	3,224.54 ± 0.02^b	S→T (S. houtenae*)
S. enterica	RNase E	119.3	2,706.37 ± 0.00^b	S→T (S. arizonae*)
			2,706.37 ± 0.00^b	P→T, S→T (S. houtenae*)
			3,046.42 ± 0.02^b	T→A, S→T (S. arizonae*)
			3,046.42 ± 0.02^b	T→A, H→Y (S. houtenae*)
S. houtenae	Flagellar synthesis protein FlgN	16.0	3,102.61 ± 0.05	S→A (S. arizonae)
S. houtenae	Flagellar synthesis protein FlgN	16.0	3,102.61 ± 0.05	N→D (S. enterica*)
S. houtenae	Isoprenoid biosynthesis protein	22.9	2,763.46 ± 0.02	S→A (S. arizonae*)
S. houtenae	Isoprenoid biosynthesis protein	22.9	2,763.46 ± 0.02	E→D (S. enterica*)
S. houtenae	NlpB/DapX lipoprotein	36.9	2,504.25 ± 0.01	D→E, V→P (S. arizonae)
S. houtenae	NlpB/DapX lipoprotein	36.9	2,504.25 ± 0.01	V→A (S. enterica*)
S. houtenae	Outer membrane protein A	38.4	3,521.70 ± 0.02^b	A→T, Y→GA, T→Y (S. arizonae*)
S. houtenae	Outer membrane protein A	38.4	3,521.70 ± 0.02^b	A→V, Y→GP (S. enterica*)

The measured peptide masses are given as the arithmetic mean calculated from the values of the three replicates of the subspecies, and the corresponding standard deviations are presented. Specific amino acids in the biomarker peptides of a subspecies and their exchanges in peptides of the other subspecies are given. All numbers were rounded to the second digit after the comma. The NCBI database was used.

Biomarker peptide found in all investigated ppm windows (±25, ±50, and ±100 ppm).

*, a sequence analogous to the biomarker peptide was observed; •, a shorter or longer peptide sequence containing at least one relevant amino acid exchange was observed.