文摘
A novel, sensible, and specific fluorescent biosensor of human calmodulin (hCaM), namely hCaM L39C-mBBr/V91C-mBBr, was constructed. The biosensor was useful for detecting ligands with opposing fluorescent signals, calcium ions (Ca2+) and CaM inhibitors in solution. Thus, the device was successfully applied to analyze the allosteric effect of Ca2+ on trifluoroperazine (TFP) binding to CaM (Ca2+Kd = 0.24 渭M 卤 0.03 with a stoichiometry 4.10 卤 0.15; TFPKd 5.74鈥?.53 渭M depending on the degree of saturation of Ca2+, with a stoichiometry of 2:1). In addition, it was suitable for discovering additional xanthones (5, 6, and 8) with anti-CaM properties from the fungus Emericella 25379. The affinity of 1鈥?b>5, 7, and 8 for the complex (Ca2+)4-CaM was excellent because their experimental Kds were in the nM range (4鈥?98 nM). Docking analysis predicted that 1鈥?b>8 bind to CaM at sites I, III, and IV as does TFP.