When the FP concentration was increased, the emission peak of CaM decreased in each case, and the maximum emission wavelength increased from 330 to 350 nm. The interaction between PDE and FP is shown in Figure 8B. The emission selleck peak of PDE also decreased, accompanied by an increase in FP concentration, while the maximum emission wavelength increased from 335 to 360 nm. When equal concentrations of CaM and PDE were mixed with Ca2, the emission intensity of the CaM Ca2 PDE system increased significantly from 400 to 3,400, indicating that the CaM Ca2 PDE enzyme system exhibited a strong intermolecular interaction. Figure 8D shows the emission spectra of the CaMCa 2 PDE system with increasing concentrations of FP, the emission intensity apparently decreased as the FP concentration increased, and the maximum emission wavelength increased simultaneously by 20 nm. In contrast, the emission intensity of the CaM Ca2 PDE system decreased slightly as the HF concentration increased. According to the classical Stern Volmer equation : F0F1zKq?Q where F0 is the emission intensity in the absence of quencher, F is the emission intensity in the presence of quencher, Kq is the quenching constant and is the quencher concentration. The shape of the Stern Volmer plots can be used to characterize the quenching as either predominantly dynamic or static.
Plots of F0/ F versus appear to be linear and Kq depends on temperature. The emission quenching on addition of FP to the CaM Ca2 PDEsystem at 25uC is shown in Figure 8E. F0/F lines at 25uC and 37uC, respectively, are shown in Figure 9A.
The experiments demonstrated that a higher temperature was associated with a lower the slope of the quenching curve for the CaM Ca2 PDE system in presence of different amounts of FP. The combination of FP with CaM Ca2 PDE was a single static quenching process. The quenching data were therefore analyzed according to the equations ATM inhibitor review eF0{FT{1F0 {1zK{1F0 {1 ?Q {1 Line weaver Burk plots are shown in Figure 9B. The linearlydependent coefficients were 0.99 and 0.998. According to this equation, the binding constants at different temperatures could be calculated as k37uC 4.86104 L/mol, k25uC 6.246104 L/mol, respectively. These results showed that FP, but not HF, formed noncovalent complexes and showed high binding affinity with CaM Ca2 PDE. Discussion Most nontoxic dietary flavonoids are known to behave as general cell growth inhibitors in many kinds of cultured human cancer cell lines. Many flavonoids can perturb cell cycle progression and induce G1 or G2/M cell cycle arrest, which is a fundamental activity in the process of cell proliferation. The present results demonstrated that both HF and FP were able to significantly inhibit proliferation in human cervical cancer HeLa cells in dose and time dependent manners, with FP having a much greater effect than HF.