Fluorescence emission peak

According to the Kuwabara-Wassink paper, the purified luciferin in aqueous neutral buffer solution showed an absorption maximum at 320 nm, and a fluorescence emission peak at 490 nm. The luminescence emission maximum measured with Airth s fungal luciferase system was 524 nm at pH 6.5, whereas the chemiluminescence emission maximum of the luciferin with H2O2 plus a droplet of strong NaOH plus ferrous sulfate was 542 nm. No information was reported on the chemical nature of the luciferin. 

When a photoprotein solution (1.3 ml) was shaken with ethanol (0.7 ml) containing one drop of concentrated HC1 and then the mixture was extracted twice with 2 ml each of ethyl acetate, about 75% of the chromophore was extracted into the ethyl acetate extract. The chromophore isolated showed an absorption peak at 398 nm in neutral methanol (Fig. 10.2.5). The isolated chromophore was practically non-fluorescent, like the native photoprotein. However, the acidification of a methanolic solution with HC1 resulted in a sharpening and two-fold increase of the 398 nm absorption peak, accompanied by the appearance of fluorescence. In aqueous 0.1 M HC1, two fluorescence emission peaks (595 nm and 650 nm) were found, together with a corresponding excitation peak (400 nm). Treatment of the 398 nm absorbing chromophore with 0.1 M NaOH resulted in a rapid loss of the 398 nm absorption peak. Dithionite did not affect the 398 peak, suggesting that the chromophore does not contain Fe3+. 

Porphyridium species are the sources of fluorescent pink color. The main Porphyridium phycobiliproteins are B-phycoerythrin and b-phycoerythrin. Maximum absorbance of a 1% solution of B-phycoerythrin in a 1-cm cuvette is at 545 inn, and the fluorescence emission peak is at 575 inn molecular weight is 240 kda. Batch culture of Porphyridium species outdoors yields approximately 2(X) mg of colorant per liter of culture after 3 days the phycoerythrin level in the colorant is about 15%. A higher concentration of phycoerythrin, up to 30%, can be achieved under optimal algal culture conditions. 

Fluorescent probes are divided in two categories, i.e., intrinsic and extrinsic probes. Tryptophan is the most widely used intrinsic probe. The absorption spectrum, centered at 280 nm, displays two overlapping absorbance transitions. In contrast, the fluorescence emission spectrum is broad and is characterized by a large Stokes shift, which varies with the polarity of the environment. The fluorescence emission peak is at about 350 nm in water but the peak shifts to about 315 nm in nonpolar media, such as within the hydrophobic core of folded proteins. Vitamin A, located in milk fat globules, may be used as an intrinsic probe to follow, for example, the changes of triglyceride physical state as a function of temperature [20]. Extrinsic probes are used to characterize molecular events when intrinsic fluorophores are absent or are so numerous that the interpretation of the data becomes ambiguous. Extrinsic probes may also be used to obtain additional or complementary information from a specific macromolecular domain or from an oil water interface. 

The synthetic GFP chromophore analogue (2-(4-nitrophenyl)-5-(4-cyanophenyl methylidene) imidazol-4-one ), was synthetized according to ref [6]. It was recrystallized from ethanol and characterized by 1H-NMR through their typical proton signal at 7.1 2 ppm. High concentrated solutions of approximately 3.10 3M were prepared by dissolution in dioxan. The photophysical characteristics of this analogue were determined from the UV absorption spectra and from steady-state fluorescence. An extinction coefficient of 20700 M cm 1 was determined at the maximum absorption wavelength at 406 nm. The fluorescence emission peaks at 508 nm. 

With the probe position moving toward the center of the aqueous channel, we detected more ultrafast and less slow solvation components. Note the negligible change of the quasi-bound water contributions, which indicates the complete detection of the two layers of quasi-bound water by all four Trp-probes. For TME, the fluorescence emission peak shifts to 338 nm, and its location moves to the lipid interface (Fig. 18). We did observe a smaller fraction of slow solvation dynamics decreasing from 53% in TBE to 43% in TME and an increase of the ultrafast component from 17% to 26%. The corresponding anisotropy dynamics drops from 726 to 440 ps with a less hindered local motion at the lipid interface. 

FIGURE 6. Postulated excitation energy transfer sequence between the chlorophyll-proteins of photosystem I, with low temperature fluorescence emission peaks shown. This model has proven useful in predicting and interpreting the fluorescence emission spectra of barley mutants lacking one or more of the chlorophyll-proteins of photosystem I. Thus the viridisk23 mutant fluoresces at 720 nm and completely lacks LHCI, whereas the chlorophyll b-less mutant fluorescences at 730 nm, and LHCI can be detected by immunoblotting. 

The emission peak of fluorescein is still in the same position at all LTF concentrations. The reason for this is that the environment of the fluorescein on LCA was not affected or modified with binding of LTF on LCA. However, it is important to note that the fluorescence emission peak of fluorescein is not very sensitive to all modifications occurring in its proximity. Other probes have a much more sensitive emission peak than... 

Figure 15.1 shows the fluorescence emission spectrum of BSA Trp residues in the absence (spectrum a) and presence of TNS (b), both recorded at pH 3. First, we see that the fluorescence emission peak (325 nm) of the Trp residues of the protein decreases to almost zero in the presence ofTNS, while an important emission peak at 435 nm characterizing the fluorescence emission ofTNS bound to BSA appears. 

Figure 15.2 shows fluorescence emission spectra of BSA in the absence (a) and presence (b) of TNS, both recorded at pH 7. The fluorescence emission peak of Trp residues is... 

Aminophenoxazone dyes were studied by Otsuki and Taguchi94 with respect to their solvatochromic behavior in non-hydrogen-bonding polar solvents. The absorption spectra of 7-A,A-dimethylamino-3-phenoxazone (77), its 7-A,A-diethylamino analog and its 1-methyl analog were measured in several neat solvents and in aqueous dioxane solutions and the peak positions correlated linearly with the jt scale. The fluorescence emission peak, however, was not linear with jt. ... 

Porphyria Urine PBG/ALA Urine Porphyrins Fecai Porphyrins Erythrocyte Porphyrins Plasma Fluorescence Emission Peak... 

Beta and y-CD monofunctionalized at the 6-0- position with 9-an-thracenecarboxylate, 62 (/ -) and 63 (y-), have a similar broad fluorescence emission peaked at 485-490 nm. However, the absorption spectrum of 63... 

Both chlorophyll and PS I are present and functional in heterocysts (1,5,6,7), but there is no oxygen evolution by heterocysts (6,7). The low variable fluorescence yield and low fluorescence emission at 695 nm for purified heterocysts provide evidence that heterocysts lack PS II (5,7) however, some heterocysts have been reported to give a fluorescence emission peak at 690 nm (8). The amount of biliproteins in heterocysts from different strains of cyanobacteria appears to be highly variable (2,7,8,9,10,11). 

Our data on the fluoresence emission spectra is in apparent contradiction to that reported in (9). We were unable to reproduce the observed shift in the fluorescence emission peak under our conditions or those described in (9). 

The fluorescence emission peak at 680nm decreased with DEPC... 

The chlorophyll fluorescence emission peak decreased 10 times with NBD-Cl (1000 pM) and about 3 times with DEPC (1000 pM). Both Tyr and His residues may be involved with the chlorophyll antenna as... 

The fluorescence emission peak is near 680 nm for either 630 nm or 692 nm excitation. A time resolved Decay Associated Spectrum (DAS) of the data in Fig 1 is shown in Fig 2. The three signals with large positive amplitudes have lifetimes very close to those observed with 630 nm excitation [ref (2) and Fig 3a] confirming the trap-limited model. In addition there is a very fast component with a 17 ps lifetime with both positive and negative amplitudes indicating that it is associated with the energy transfer processes between the pigments (1,4). 

Figure 3. Model for the structure of photosystem I, showing the distribution of chlorophyll a and b between the component chlorophyll-proteins. Excitation energy transfer may occur in a linear sequence from LHCII (under state 2) to CPI, The fluorescence emission peaks for the individual chlorophyll-proteins are also shown, although are usually shifted in vivo, when they are associated with other chlorophyll-proteins.

Iron(iii) tetrasulfonatophthalocyanine (FeTSPc), a mimetic enzyme, is used to catalyse the oxidation reaction of thiamin to produce thiochrome in the presence of H2O2 (Chen et al. 1999). Thiamin is oxidized to thiochrome by the catalytic activity of FeTSPc in the presence of H2O2 in alkaline medium, which exhibits an enhanced fluorescence emission peak at 440 nm when excited at 375 nm with the fluorogenic substrate, L-tyrosine (Chen et al. 1999). The fluorescence intensity is increased linearly with the concentration of thiamin in the range of 1.0 x 10 to 1.0 x lO mol The limit of detection is 4.3 X 10 mol and the relative standard deviation is 2.2% for six repeated... 

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