Intrinsic fluorescence temperature effect

Rush et al.51 first described the effect of thermally induced conformational changes on migration behavior of a-lactalbumin. A sigmoidal dependency of the viscosity-corrected mobility on temperature was observed. Transition temperature also agreed closely with that determined by intrinsic fluorescence measurements. 

We have observed three types of effects on the structures of enzymes as the temperature is lowered in cryosolvents (1) no apparent change in the protein conformation, with the possible exception of decreased mobility of the surface side chains (2) conformational transitions, usually marked by little effect on the catalytic properties and (3) increased association of subunits. In most cases no detectable effects of decreasing temperature on the enzyme s structure have been detected by such procedures as monitoring the intrinsic fluorescence (16), or intrinsic visible absorbance in the case of flavin enzymes (Fink and... 

There are also several temperature-dependent experiments that rely upon the intrinsic fluorescence of the polymer. The number of polymers that exhibit intrinsic fluorescence makes these experiments limited, especially since this type of fluorescence is generally weak and not amendable for thin film measurements. These types of experiments are preferred when possible because they are not complicated by interpretations about where or what the dye is doing in the polymer. However, these measurements also come with their own set of concerns. It is generally understood that the fluorescent intensity coming from a polymer is dependent on the refractive index and absorption coefficients of the polymer, which are also temperature dependent. However, estimates indicate that this effect is not greater than a few percent on the measured intensities. There are also reports that the fluorescence intensity can change isothermally with physical ageing of the polymer. ... 

In summary, the use of fluorescence lifetime monitoring for temperature sensing at high temperatures is based on the phenomenon of thermal quenching of fluorescence, while this phenomenon is j u st the very obstacle that blocks the extending of the measurement further into higher temperatures. Therefore, fluorescence thermometry is intrinsically more effective for measurement within moderate temperature regions, due to this fundamental nature of the fluorescence emission itself. 

Temperature has no effect on intrinsic transition probabilities or fluorescence or phosphorescence but emission characteristics may be affected by other temperature dependent nonradiative competitive processes. 

Among the best well-known examples of photostability after UV radiation, the ultrafast nonradiative decay observed in DNA/RNA nucleobases, has attracted most of the attention both from experimental and theoretical viewpoints [30], Since the quenched DNA fluorescence in nucleobase monomers at the room temperature was first reported [31] new advances have improved our knowledge on the dynamics of photoexcited DNA. Femtosecond pump-probe experiments in molecular beams have detected multi-exponential decay channels in the femtosecond (fs) and picosecond (ps) timescales for the isolated nucleobases [30, 32-34], The lack of strong solvent effects and similar ultrafast decays obtained for nucleosides and nucleotides suggest that ultrashort lifetimes of nucleobases are intrinsic molecular properties, intimately... 

Figure 3 The effect of temperature on the rate of evolution, fluorescence quenching parameters qQ and qE, and the calculated intrinsic PSII yield, p for cells of Dunaliella illuminated at a PFD of 550maole quanta/nF/s...

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