| Deficiency in factor IXa (FIXa) results in Hemophilia B and FIXa over-expression has been implicated in coagulopathies such as venous thrombosis and thromboembolic stroke. Therefore, studying the regulation of FIXa activity is of particular significance. In this thesis, four pentapeptide library substrates, based on the extended antithrombin sequence, were used to probe the FIXa active site in response to modulation by Ca++, low molecular weight heparin, and ethylene glycol. The results from this thesis (i) provide evidence for a practical and effective application of MALDI-TOF MS technology in detecting peptide fragments from pentapeptide library substrates, (ii) confirm FIXa responds differently in the presence/absence of these effectors, (iii) showed Ca++ enhances FIXa reactivity with the P2 position of the substrate suggesting modulation of the S2 subsite of the FIXa active site by Ca ++, and (iv) showed that ethylene glycol displays a similar enhancement with respect to the P3 position suggesting that ethylene glycol modulates the S3 subsite of the FIXa active site. |
