Thrombin Activation via Serum Preparation Is Not the Root Cause for Cardiac Troponin T Degradation.

To the Editor:We read with interest the recent article by Katrukha et al. concerning thrombin-mediated degradation of human cardiac troponin T (cTnT) in serum (1). In their study, Katrukha and coworkers confirmed the finding of Streng et al. that human coagulation factor II (thrombin) is a strong mediator of cTnT degradation (2). They compared cTnT degradation in serum and heparin plasma collected simultaneously from the same patients with acute myocardial infarction (AMI), revealing substantial differences in cTnT fragment composition. They also performed in vitro experiments in which troponin T, thrombin, and hirudin were supplemented in various combinations. In addition, the cleavage site in cTnT was localized by use of mass spectrometry and probing of different proteolytic fragments with the use of various antibodies. Their main conclusion was that the primary 29-kDa cTnT fragment was mainly formed because of thrombin activation during serum preparation.We believe that the evidence for thrombin as one of the main proteases for cTnT degradation is convincing. However, we disagree with their final conclusion because there is published evidence suggesting …