Extra Leader Sequence Affects Immunoactivity of Cardiac Troponin I

Abstract
Cardiac troponins are considered the preferred cardiac markers for diagnosis of acute myocardial infarction ( 1). The development and evaluation of cardiac troponin I immunoassays require purified and immunochemically stable antigen for the production of calibrators and controls. Cardiac troponin I (cTnI) purified from human heart has traditionally been used for such purposes. However, cTnI is unstable and prone to degradation during the process of purification from human heart tissue. Recombinant protein is favored over the protein purified from tissue because it is easier to purify, safer to handle, and has unlimited availability and good reproducibility. In physiological conditions, troponin C (TnC) and TnI along with troponin T (TnT) form an integral protein, designated as troponin complex. To study the immunoactivity of TnI in a clinically relevant form, it is imperative to put TnI in the context of the other two subunits, TnC and TnT.