Table 1.

Identification of cTnI components in ESI/FTMS spectra of postmortem (b) and fresh transplant (c) human heart tissue samples.

Identification 1	Observed Mr (Da)	Calculated Mr2(Da)	Error (ppm)
cTnIb,c	23917.96	23917.83	5.4
Major C-terminally truncated isoforms
cTnI(II)b	23701.96	23701.75	8.9
cTnI(III)b	23554.86	23554.68	7.6
cTnI(IV)b	23426.72	23426.59	5.5
Phosphorylation products
pcTnIb,c	23997.95	23997.90	2.1
ppcTnIb,c	24077.84	24077.86	−0.8
pcTnI(II)b	23781.60	23781.72	−5.0
ppcTnI(II)b	23861.67	23861.68	−0.4
pcTnI(III)b	23634.88	23634.65	9.7
ppcTnI(III)b	23714.68	23714.62	2.5
pcTnI(IV)b	23506.64	23506.55	3.8
ppcTnI(IV)b	23586.44	23586.52	−3.4
Major degradation products
cTnI Y[28–206]Kb	20605.22	20605.19	1.5
cTnI Y[28–205]Kb	20477.12	20477.10	1.0
cTnI Y[25–209]Sb,c	21359.60	21359.59	0.5
cTnI Y[25–207]Kb	21143.46	21143.50	−1.9
cTnI Y[25–206]Kb	20996.57	20996.56	0.5
Minor degradation products
cTnI A[1–148]Ib	16990.38	16990.46	−4.7
cTnI Y[28–209]Sb	20969.32	20969.40	−3.8
cTnI Y[25–205]Kb	20868.30	20868.32	1.0
cTnI S[23–171]Hb	17070.52	17070.27	14.6
TnI P[32–209]Sc	20504.48	20504.70	−10.7

¹Roman numerals indicate four different C-terminal truncated isoforms of C-terminally acetylated cTnI (I, residues 1–209; II, residues 1–207; III, residues 1–206; IV, residues 1–205). Subscript p stands for monophosphorylation and pp stands for bisphosphorylation.

²Calculated M_r is the most abundant isotopic mass based on the amino acid sequence of entry name TNNI3_human from the Swiss-Prot sequence database.