Phosphoryl hóa thay đổi cấu trúc và cấu tạo của phân tử cTnI, và mối quan hệ tương tác giữa các thành phần của khu phức hợp troponin. Vì vậy, phosphoryl hóa có thể thay đổi sự tương tác của một số kháng thể với các epitope của họ | 178 Katrukha could be detected in patients blood. It was demonstrated that about the half of cTnl circulating in patients blood is phosphorylated by PKA 4 43 but it is unknown yet what part of circulating cTnI is phosphorylated by PKC. Phosphorylation changes the structure and conformation of the cTnI molecule and the affinity of interaction between the components of the troponin complex. Thus phosphorylation can change the interaction of some antibodies with their epitopes. Several MAbs recognizing only phosphorylated cTnI or vice versa only dephosphorylated protein were described in literature during the last few years 4 43 44 . If such antibodies were to be used in cTnI immunoassay a considerable part of the antigen in a patient s blood would remain undetected. Hence it is preferable that the antibodies selected for the immunoassay development should be specific to the epitopes different from the sites of phosphorylation so that interaction of such antibodies with the antigen will be unaffected by any type of phosphorylation. Oxidation of cTnl cTnI has two cysteines at 79 and 96 positions 11 that can be oxidized or reduced in vitro. Oxidation reduction changes the structure and the conformation of the protein and thus changes the interaction of some antibodies with the number of epitopes. Wu et al. 5 demonstrated that three out of nine tested commercially available assays were sensitive higher response to the oxidation of the antigen whereas for others there was no difference for the form of the protein tested. Although it is still unclear in what form oxidized or reduced cTnI releases from damaged cardiac tissue after AMI and circulates in human blood it is preferable that antibodies used in the assay recognize both forms with the same efficiency. Complexes of cTnl with Polyanions As mentioned previously cTnI is a highly basic protein with pI and more or less equal distribution of basic amino acid residues along the molecule. At physiological pH cTnI .
