Cardiac troponin T degradation in serum is catalysed by human thrombin

• Published in: Biochemical and biophysical research communications 2016-12, Vol.481 (1-2), p.165-168
• Main Authors: Streng, Alexander S., de Boer, Douwe, van Doorn, William P.T.M., Kocken, Jordy M.M., Bekers, Otto, Wodzig, Will K.W.H.
• Format: Article
• Language: English
• Subjects: Cardiac troponin T; Catalysis; Fragmentation; Humans; Myocardium - chemistry; Myocardium - metabolism; Proteolysis; Serum - chemistry; Serum - metabolism; Thrombin; Thrombin - chemistry; Thrombin - metabolism; Troponin I - blood; Troponin I - chemistry; Western blot
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2016.10.149

Cardiac troponin T (cTnT) has been shown to be present in fragmented forms in human serum after acute myocardial infarction (AMI). While calpain-1 and caspase-3 have been identified as intracellular proteases able to cleave the N-terminus of cTnT, it is still unclear which proteases are responsible for the extensive and progressive cTnT fragmentation observed in serum of AMI-patients. In this pilot study we have investigated the possibility that human thrombin may be involved in this process. Purified human cTnT was spiked in unprocessed and deproteinated serum in the presence or absence of either purified human thrombin or PPACK thrombin inhibitor. After immunoprecipitation, SDS-PAGE and Western blotting we observed an increase in cTnT fragmentation when purified thrombin was added to deproteinated serum. Consequently, the addition of thrombin inhibitor to unprocessed serum resulted in a decrease of cTnT fragmentation. Our results suggest that multiple enzymes are involved in cTnT degradation, and that thrombin plays an important role. •Cardiac troponin T (cTnT) fragmentation is modelled by incubation at 37 °C in serum.•The addition of PPACK thrombin inhibitor reduced cTnT fragmentation.•Incubation of cTnT with purified thrombin in buffer increased cTnT fragmentation.•Thrombin is proposed as a protease targeting cTnT in human serum.