Fluorescence quenching methods have been used to study interactions of anionic phospholipids with the potassium channel KcsA from Streptomyces lividans. Quenching of the Trp fluorescence of KcsA reconstituted into mixtures of dioleoylphosphatidylcholine (DOPC) and an anionic phospholipid with dibromostearoyl chains is more marked at low mole fractions of the brominated anionic phospholipid than...

Under external magnetic fields (B) from 0 to 10T, we have examined the magnetic quenching of the fluorescence from several electronic excited states of gas phase molecules: S10 0 0 and 6a 1 0 vibronic bands of pyrimidine, 6V and 10V band regions of CS2, and e C(132) and (150) vibronic bands of SO2. A major result of this work is the observed saturation of the magnetic quenching due to the “dire...

Seasonal differences have been observed in the ability of desiccated mosses to dissipate absorbed light energy harmlessly into heat. During the dry summer season desiccation-tolerant mosses were more protected against photo-oxidative damage in the dry state than during the more humid winter season. Investigation of the differences revealed that phototolerance could be acquired or lost even unde...

The photosystem II (PSII) protein PsbS and the enzyme violaxanthin deepoxidase (VDE) are known to influence the dynamics of energy-dependent quenching (qE), the component of nonphotochemical quenching (NPQ) that allows plants to respond to fast fluctuations in light intensity. Although the absence of PsbS and VDE has been shown to change the amount of quenching, there have not been any measurem...

The steady state absorption and fluorescence spectroscopic properties of the xanthophylls, violaxanthin, zeaxanthin, and lutein, and the efficiencies of singlet energy transfer from the individual xanthophylls to chlorophyll have been investigated in recombinant CP26 protein overexpressed in Escherichia coli and then refolded in vitro with purified pigments. Also, the effect of the different xa...

In higher plants, high light conditions trigger the activation of non-photochemical quenching (NPQ), a process of photoprotective light energy dissipation, via acidification of the chloroplast lumen. Spectral changes occurring in the neoxanthin domain of the major light harvesting antenna complex (LHCII) have previously provided indirect evidence of a protein conformational switch during NPQ. W...

The relationship between the carotenoid zeaxanthin, formed by violaxanthin de-epoxidation, and nonphotochemical fluorescence quenching (q(NP)) in the light was investigated in leaves of Glycine max during a transient from dark to light in 2% O(2), 0% CO(2) at 100 to 200 micromoles of photons per square meter per second. (a) Up to a q(NP) (which can vary between 0 and 1) of about 0.7, the zeaxan...

Binding of gefitinib (GEF), a promising anticancer drug to human serum albumin (HSA), the major transport protein in blood circulation was investigated using fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy as well as computational modeling. Fluorescence quenching of HSA upon GEF addition was found to be a static quenching process, as revealed from the decreasing trend o...

Bioactive imidazole derivative absorbs in the UV region at 305 nm. The interaction of imidazole derivative with nanoparticulate WO3, Fe2O3, Fe3O4, CuO, ZrO2 and Al2O3 has been studied by UV-visible absorption, FT-IR and fluorescence spectroscopies. The imidazole derivative adsorbs strongly on the surfaces of nanosemiconductor, the apparent binding constants for the association between nanomater...