AI Article Synopsis
- Researchers identified two transcripts (Td60 and Td101) in Triatoma dimidiata saliva that are similar to triabin, a known thrombin inhibitor found in another species.
- A recombinant version of Td60 called dimiconin was produced in E. coli, and its effects on blood coagulation pathways were studied.
- Dimiconin specifically inhibits the activation of coagulation factor XII (FXII) rather than thrombin, affecting the intrinsic pathway and highlighting a different function compared to triabin.
Article Abstract
Sequence analysis of a Triatoma dimidiata salivary gland cDNA library resulted in the identification of two transcripts (Td60 and Td101) homologous to triabin, an inhibitor of thrombin in Triatoma pallidipennis saliva. In the present study, a recombinant protein of Td60, designated dimiconin, was expressed in Escherichia coli and its activity was characterized. The resulting protein inhibited the intrinsic but not extrinsic blood coagulation pathway, suggesting that dimiconin is not a thrombin inhibitor. Measurement of the enzymatic activity of coagulation factors using chromogenic substrates revealed that dimiconin efficiently inhibited factor XIIa (FXIIa) activity in a dose-dependent manner. In addition, pre-incubation of dimiconin with FXII effectively inhibited FXIIa activity whereas dimiconin did not affect already activated FXIIa, indicating that dimiconin inhibits the activation of FXII but not the enzymatic activity of FXIIa. These results show that dimiconin is an inhibitor of the contact phase initiated by FXII activation in the blood coagulation cascade, which differs from the bioactivity of triabin.
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| http://dx.doi.org/10.1242/jeb.074211 | DOI Listing |
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