Date on Master's Thesis/Doctoral Dissertation
Maurer, Muriel C.
Factor XIII; Coagulation; Hydrogen-deuterium exchange; Mass spectrometry; Transglutaminase
One of the last events that occurs during blood coagulation, a process taken for granted on a daily basis, involves Factor XIII (FXIII) cross-linking fibrin monomers to form an insoluble clot. In plasma, FXIII-A2 is not active and exists as the heterotetramer FXIII-A2B2. Through the utilization of hydrogen - deuterium exchange (HDX) coupled with Matrix Assisted Laser Desorption ionization - Time of Flight - Mass Spectrometry (MALDI-TOF-MS), it was determined that FXIII-A2 becomes nearly uniformly protected when bound to FXIII-B2 and the FXIII-A2 ß-barrels play a major role in heterotetramer formation. After dissociation from FXIII-B2, FXIII-A2 has the ability to become activated in the presence of Ca2+. The regions/residues of FXIII-A2 Ca2+ affects during activation were identified using HDX. It is debated whether FXIII-A2 undergoes an open conformation during activation. Transglutaminase 2 (TG2) has been observed crystallographically in an open conformation. HDX was utilized to compare the conformational dynamics of Transglutaminase 2 in solution to that of FXIII-A2. The increase in exposure between the catalytic core and ß-barrels of TG2 yields evidence of an open conformation. A structural comparison of FXIII-A2 and TG2 identified steric hinderance within the A2 dimer that could thwart a similar conformational change. Once activated physiologically, FXIII-A2 is solely responsible for forming the cross-links between fibrin monomers. The aC (233 - 425) region of fibrin contains three reactive Gin residues and acts as a substrate for FXIII. Fibrin aC (233 - 425) was expressed and its structure investigated via 15N-HSQC when in solution with FXIII-A2. The integral role of FXIII-A2 in the coagulation cascade leads to a dire need for investigating its conformational dynamics during activation. The research herein provides a stronger knowledge of FXIII-A2 structural changes during activation and outlines FXIII-A2 interactions with 82 and the fibrin aC domain. This progress in understanding FXIII-A2 dynamics could lead to improved treatments for excessive bleeding and thrombosis.
Woofter, Richard Tatum, "Conformational dynamics leading to activation of the transglutaminase factor XIII." (2011). Electronic Theses and Dissertations. Paper 1591.