. 2019 Jan 28;9:806. doi: 10.1038/s41598-018-37512-8

Table 2.

Annotation of variables with VIP values higher than 1.35 (highlighted in bold) in at least a pairwise PLS-DA model from the CE-MS metabolomics analysis of PKD samples.

Level of assignment	Annotation	Abbreviation	Migration time (min)	Detected specie	Experimental m/z	m/z error	VIP values of PLS-DA
Level of assignment	Annotation	Abbreviation	Migration time (min)	Detected specie	Experimental m/z	m/z error	Wt0 vs Wt14	Wt0 vs MCK	MCK vs ESCK
Confirmed with standard	Creatinine	Cre	13.4	[M+H]⁺	114.0671 115.0697	0.9 mDa	2.03 1.75	1.56 1.29	1.30 1.36
	Carnitine	Carn	15.4	[M+H]⁺	163.1159 (isotopic profile of 162.1139) 164.1173	1.4 mDa	0.37 0.31	0.91 0.95	1.55 1.58
	Creatine	Cr	17.0	[M+H]⁺	133.0796 (isotopic profile of 132.0782)	1.4 mDa	1.49	1.42	0.20
	Glutamine	Gln	21.0	[M-NH₃+H]⁺	130.0503	0.5 mDa	1.27	1.42	0.59
	Betaine	Btn	22.9	[M+H]⁺	119.0899 (isotopic profile of 118.0884)	2.1 mDa	0.12	0.44	1.39
Tentative annotation	1-methylhistidine	mHis	14.6	[M+H]⁺	170.0925 171.0955	0.1 mDa	2.31 2.29	2.17 2.20	0.25 0.26
	Acetylcholine	Ach	14.7	[M+H]⁺	146.1178	0.2 mDa	0.91	1.47	0.72
	4-Guanidinobutanoic acid	Gba	15.0	[M+H]⁺	146.0927	0.3 mDa	1.04	1.44	1.65
	2-Aminooctanoic acid	AoA	15.2	[M+H]⁺	160.1334 161.1367	0.2 mDa	1.53 1.54	1.81 1.86	0.94 0.96
	Methylguanine (different isomers are possible)	mGu	15.2	[M+H]⁺	166.0725	0.2 mDa	0.46	0.61	1.55
	γ-L-Glutamylputrescine or N5-(1-imino-3-butenyl)-L-ornithine	Gput	15.4	[M-H₂O+H]⁺	200.1393	0.6 mDa	1.55	1.71	1.01
	Formylisoglutamine	fGln	15.4	[M+H]⁺	175.0715	0.2 mDa	0.14	1.04	1.60
	Imidazolelactic acid	ILA	16.3	[M+H]⁺	157.0609	0.1 mDa	1.66	1.66	0.73
	Asn-Hydroxyproline or Hydroxyprolyl-Asn	P1	16.5	[M+H]⁺	246.1083	0.1 mDa	1.41	1.29	1.57
	Argininic acid	ArgA	16.5	[M+H]⁺	176.1030	0.0 mDa	0.20	0.19	1.65
	Propionyl-L-carnitine	Pcarn	16.6	[M+H]⁺	218.1386 219.1417	0.1 mDa	1.36 1.37	0.92 0.90	1.28 1.27
	Homocitrulline	Hcit	16.8	[M+H]⁺	190.1185	0.1 mDa	1.09	0.30	1.64
	Glycyl-lysine or lysyl-glycine	P2	17.4	[M+H]⁺	204.1342	0.1 mDa	0.68	0.28	1.63
	N-α-Acetyl-L-arginine	Aarg	17.7	[M+H]⁺	217.1286	0.9 mDa	1.75	0.82	1.54
	3-Hydroxyisovalerylcarnitine	HIVC	17.7	[M+H]⁺	262.1647	0.2 mDa	2.07	0.43	1.47
	(1) Phe-Thr or Thr-Phe (2) Hydroxyproline-Leu(Ile), or Leu(Ile)-Hydroxyproline	P3	18.5	[M+H]⁺ (1) [M+Na]⁺ (2)	267.1339 268.1370	0.9 mDa	1.70 1.68	1.57 1.86	1.61 1.65
	2-[3-carboxy-3-(methylammonio)propyl]-L-histidine	CMHis	19.0	[M+H]⁺	271.1400	0.1 mDa	0.52	1.27	1.64
	Proline betaine	ProB	23.1	[M+H]⁺	144.1023	0.4 mDa	1.86	2.18	1.39
	γ-carboxyglutamic acid	Gla	32.1	[M+H]⁺	192.0501	0.2 mDa	1.26	0.83	1.35
	5-Hydroxyindoleacetylglycine	hINaG	32.1	[M-H₂O+H]⁺	231.0764	0.6 mDa	1.88	1.67	1.56
	Pantothenic acid	PA	32.2	[M-H₂O+H]⁺	202.1074	0.5 mDa	0.06	0.15	1.45