Structural analyses fluorescence properties

As shown above, the intrinsic fluorescence spectra of proteins as well as coenzyme groups and probes shift within very wide ranges depending on their environment. Since the main contribution to spectral shifts is from relaxational properties of the environment, the analysis of relaxation is the necessary first step in establishing correlations of protein structure with fluorescence spectra. Furthermore, the study of relaxation dynamics is a very important approach to the analysis of the fluctuation rates of the electrostatic field in proteins, which is of importance for the understanding of biocatalytic processes and charge transport. Here we will discuss briefly the most illustrative results obtained by the methods of molecular relaxation spectroscopy. 

What follows is a brief summary of the structural and spectroscopic properties of 2AP to provide a context for a discussion of how it has been and could be used to monitor RNA folding and dynamics. Several examples of its incorporation into RNA molecules are then discussed, noting how its fluorescence has been interpreted in the context of specific RNA properties. Since data analysis is a large part of fluorescence measurements, steady-state and time-resolved data are presented, including problems and pitfalls in their interpretation. 

Narasimhulu, S, 1988, Quenching of tryptophanyl fluorescence of bovine adrenal P-450c-2i and inhibition of substrate binding by acrylamide. Biochemistry. 27 1147-1153. Neyroz, P., Menna, C., Polverini, E. and Masotti, L. 1996, Intrinsic Fluorescence Properties and Structural Analysis of pi 3 from Schizosaccharomyces pombe Journal of Biological Chemistry. 271, 27249-27258. 

Mohler R, White W (1994) Influence of structural order on the luminescence of oxide spinels manganese activated spinels. Mater Res Bull 29 1109-1116 Moine B, Pedrini C, Duloisy E et al (1991) Fluorescence properties of Cu + ion in borate and phosphate glasses. J De Phys IV LC7-289-C7-292 Moncorge R, Cormier G, Simkon D, Capobianco J (1991) Fluorescence analysis of chromium doped forsterite (Mg2Si04). IEEE J Quantum Electron 27 114-120 Moncorge R, Manaa H, Boulon G (1994) Cr and Mn active centers for new solid state laser materials. Opt Mater 4 139-144... 

Such ambiguity and also the low structural resolution of the method require that the spectroscopic properties of protein fluorophores and their reactions in electronic excited states be thoroughly studied and characterized in simple model systems. Furthermore, the reliability of the results should increase with the inclusion of this additional information into the analysis and with the comparison of the complementary data. Recently, there has been a tendency not only to study certain fluorescence parameters and to establish their correlation with protein dynamics but also to analyze them jointly, to treat the spectroscopic data multiparametrically, and to construct self-consistent models of the dynamic process which take into account these data as a whole. Fluorescence spectroscopy gives a researcher ample opportunities to combine different parameters determined experimentally and to study their interrelationships (Figure 2.1). This opportunity should be exploited to the fullest. 

The name lepidopterene refers to the hydrocarbon 113 (L) whose butterflylike molecular shape was first revealed by X-ray diffraction analysis [129,130]. The structured electronic absorption spectra of lepidopterenes around 270 nm closely resemble that of 9,10-dihydroanthracene (see Figure 31). However, in terms of excited state properties, lepidopterenes have very little in common with 9,10-dihydroanthracene, which in solution fluoresces with a quantum yield of 0.16. By contrast, photoexcitation of lepidopterenes leads mainly to intramolecular exciplexes of 7i-chromophorically substituted anthracenes in an adiabatic process, for which both the molecular topology... 

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