Isoelectric point determination of cardiac troponin I forms present in plasma from patients with myocardial infarction.
BACKGROUND
Cardiac troponin I (cTnI) is a specific marker of myocardial injury. In blood of patients with cardiovascular diseases, cTnI is released as a mixture of free, complexed and post-translationally modified forms.


METHODS
The cTnI forms present in the plasma from 8 patients with acute myocardial infarction (AMI) have been analysed by two-dimensional gel electrophoresis (2-DE) and Western Blot using anti-cTnI mAb 19C7 and anti-phosphorylated cTnI (Serines 22-23) mAb 5E6.


RESULTS
After immunoextraction of cTnI in plasma samples by 19C7 and 2-DE separation, 4 different forms were detected by 19C7 in 7 out the 8 AMI plasma samples. Two 29 kDa spots corresponding to intact free cTnI forms were detected at pIs 5.2 and 5.4. However, spot with pI 5.4 was also recognized by mAb 5E6, and should be bis-phosphorylated cTnI. Two 55 kDa spots with pIs 6.6 and 6.7 could be IC complexes. CTnI forms with pIs lower than the theoretical pI were also found in free cTnI and phosphorylated cTnI purified materials.


CONCLUSIONS
2-DE analysis of AMI plasma showed the presence of acidic cTnI forms, one of them being phosphorylated. The clinical significance of these forms has to be further investigated.
Peronnet
Estelle
E
Unité Mixte de Recherche UMR 2714 CNRS-bioMérieux, IFR 128 BioSciences Lyon-Gerland, CERVI 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Becquart
Laurence
L
Martinez
Jérôme
J
Charrier
Jean-Philippe
JP
Jolivet-Reynaud
Colette
C
D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007526:Isoelectric Point; D009203:Myocardial Infarction / Q000097:blood*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry; D019210:Troponin I / Q000097:blood* / Q000737:chemistry* / Q000302:isolation & purification
D020033:Protein Isoforms; D019210:Troponin I