19841-02-2Relevant academic research and scientific papers
Synthesis, enzymatic evaluation, and docking studies of fluorogenic caspase 8 tetrapeptide substrates
Reszka, Przemyslaw,Schulz, Riad,Methling, Karen,Lalk, Michael,Bednarski, Patrick J.
experimental part, p. 103 - 117 (2010/11/02)
The synthesis, enzymatic evaluation, and molecular modeling studies of new fluorogenic tetrapeptide-based substrates selective for caspase 8, having the general structure Ac-IETD-AXX, are described. Various fluorescent reporter groups (AXX), i.e., 3- and 4-substituted coumarins and quinolin-2(1H)-ones were synthesized by von Pechmann condensation. They were subsequently coupled with the caspase-8-selective tetrapeptide Ac-IETD-OH under newly developed synthetic conditions to give the desired substrates in good yields and in high enantiomeric purity. Based on KM and Vmax values, the new compounds proved to be excellent substrates for recombinant human caspase 8. In contrast, the KM values for the same compounds as substrates for human caspase 3 were approximately 10-20-fold higher. Molecular modeling studies based on the X-ray crystal structures of both human caspases 3 and 8 revealed that there is sufficient room within both active sites to accommodate substrates with moderately bulky substituents in the 3- and 4-positions of the fluorogenic coumarins and quinolin-2(1H)-ones. Automated docking of the substrates into the active sites of both human caspases 3 and 8 with the program Auto-Dock 3 gave structures similar to the published crystallographic structures for the same tetrapeptide bound to caspase 8 in the form of an irreversible inhibitor. The calculated binding energies for the new substrates to either caspase 3 or 8 showed little difference between the substrates, consistent with the K M data. In addition, the calculated binding energies (ΔG) to caspase 8 were considerably more negative than those to caspase 3, also consistent with the KM data. A possible molecular interaction that might explain the selectivity of the IETD tetrapeptide motif for caspase 8 over caspase 3 is discussed.
Cocktails of Tb3+ and Eu3+ complexes: A general platform for the design of ratiometric optical probes
Tremblay, Matthew S.,Halim, Marlin,Sames, Dalibor
, p. 7570 - 7577 (2008/02/09)
Fluorescent and luminescent reporters that signal molecular events of interest by modulating the ratio of peaks in their emission profile have advantages over reporters that simply modulate their emission intensity, since ratiometric measurement is concentration-independent and allows them to be effective in complex contexts, such as living cells or sensor microarrays. We herein describe a general platform for the design of ratiometric probes based on a heterometallic Tb3+/Eu3+ bis-lanthanide ensemble, consisting of a mixture, or "cocktail", of otherwise identical heterometalated chelates. The chelate contains an organic photon antenna that sensitizes the Tb3+/Eu3+ luminescence. The contributions of the two metals to the composite luminescence spectrum can be tuned to the same relative scale by adjusting the stoichiometry of the cocktail, allowing subtle changes in their ratio to be accurately measured. Importantly, the ratio responds to chemical and environmental changes experienced by the photon antenna, making the system an ideal platform for the design of chemical and enzymatic probes. As proofs of concept, we describe a ratiometric probe for esterase activity and a polarity-responsive ratiometric sensor.
A concise regiospecific synthesis of 8,8-dimethyl-2H, 8H-pyrano [6, 5- h]quinolin-2-one and related compounds
Yang, Zheng-Yu,Xia, Yi,Xia, Peng,Brossi, Arnold,Lee, Kuo-Hsiung
, p. 4505 - 4506 (2007/10/03)
An efficient method for the regiospecific synthesis of 8,8-dimethyl- 2H,8H-pyrano[6,5-h]quinolin-2-one and related compounds via a Claisen rearrangement is described.
