| Dansylarginine N-(3-ethyl-1,5-pentanediyl)amide, more commonly referred to as DAPA, is a potent (Ki=10e-7M) and specific synthetic inhibitor of thrombin (1). Of special interest are the unique fluorescent properties contributed by the dansyl moiety of DAPA. When bound to thrombin, the fluorescence intensity and lifetime of the dansyl moiety are increased three fold. The enhancement of fluorescence intensity, coupled with its inhibitory properties, have made this compound extremely useful for studies involving thrombin generation (2-7). In addition to an increase in fluorescence intensity and lifetime, there is a decrease in depolarization of the excitation signal which also supports fluorescence polarization studies. The inhibitor properties of DAPA alone have been useful in a variety of applications. DAPA is routinely used as a protease inhibitor during the isolation of proteins that are susceptible to thrombin cleavage. Furthermore, by eliminating the feedback of thrombin activity during prothrombin activation, the isolation of reaction intermediates such as fragment 1.2, and meizothrombin have been made possible (7). Storage and Stability: May be stored at 4C for short-term only. For long-term storage, store at -20C. Aliquots are stable for at least 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. Additional Specifications: Extinction Coefficient: E1%1cm, 280nm=4910 (1) Special Properties: A specific and potent inhibitor of thrombin (Ki=10e-7M). Exhibits a 3-fold increase in fluorescence intensity and lifetime when bound to thrombin. |
