Tryptophan fluorescence quenching

Callis PR, Petrenko A, Muino PL, Tusell JR (2007) Ab initio prediction of tryptophan fluorescence quenching by protein electric field enabled electron transfer. J Phys Chem B 111(35) 10335-10339... 

Fluorescence determinations are important to analyze cysteine, guanidine, proteins, (LSD), steroids, a number of enzymes and coenzymes, and some vitamins, as well as several hundred more substances. A fluorometer can be used to verify conformational changes in multipartite operator recognition by. -repressor as explained in a journal article by Deb et al. (2000). Upon titration with single operators site, the tryptophan fluorescence quenches to different degrees, suggesting different conformations of the DNA-protein complexes. 

C (57). The fluorescence of either (A) tryptophan or (B) dansyl was measured as a function of time under stopped-flow conditions. Oscilloscope traces of duplicate reactions are shown in each case. Excitation was at 285 nm. Enzyme tryptophan fluorescence was measured by means of band-pass fitter peaking at 360 nm, and dansyl emission was measurea by a 430-nm cutoff filter. Scale sensitivities for (A) and (B) are 50 and 500 mV/div, respectively. The existence of the ES complex is signaled by either (A) the suppression of enzyme tryptophan fluorescence (quenching by the dansyl group) or (Ib) enhancement of the substrate dansyl group fluorescence (energy transfer from enzyme tryptophan). 

At alkaline pH the fluorescence of Class B proteins is found to be that of tyrosinate isi-i ). A report of Vladimirov and Zimina )that the fluorescence of serum and egg albumins at pH 13 is entirely due to tryptophan is probably in error the observed luminescence is most likely that of tyrosinate. Tryptophan and t3n-osinate fluorescence spectra are quite similar and hfetime measurements are sometimes necessary for definite identification. The phosphorescence of Class B proteins at alkaline pH generally has a considerable tr5 tophan component along with a dominant tyrosinate contribution 26,164). Thus, trp- -t T < > transfer appears to be very efficient at the singlet level and enhanced intersystem crossing to the tryptophan triplet at high pH 26) also contributes to the tryptophan fluorescence quenching and to the production of tryptophan phosphorescence of Class B proteins at high pH. It is possible that tyr( ) - -trp triplet transfer also occurs to an extent in some proteins. 

Chadborn, N., Bryant, J., Bain, A.J. and O Shea, P. (1999). Ligand dependent conformational equilibria of serum albumin revealed by tryptophan fluorescence quenching. Biophys. J. 76 2198-2207. 

DNA binding constants and site sizes are obtained from fluorescence titration data by nonlinear regression. The observed intrinsic tryptophan fluorescence quenching, Qobs, is defined by... 

Jang, D. J. Elsayed, M. A. Tryptophan fluorescence quenching as a monitor for the protein conformation changes occurring during the photocycle of hacteriorhodopsin under different perturbations. Proc. Nat. Acad. Set U.S.A., 1989, 86(15), 5815-5819. 

Lipid peroxidation caused a decrease in phospholipid molecule mobility both in the region of polar heads and in the region of acyl chains till the depth of at least 1.7 nm from water-lipid interface (Panasenko et al. 1991). Under relative high levels of oxidation (>6 pmol malondialdehyde/g LDL phospholipid) the polarity of lipid phase increased. The decrease in efficiency of tryptophan fluorescence quenching by nitroxide fragments incorporated into hydrophobic regions at the depth of 2 nm from water-lipid interface indicated that lipid-protein interaction was disturbed as a result of oxidation of LDL lipids. 

Fig. 20. Schematic representation of the reaction coordinate for tryptophan fluorescence quenching induced by hydrogen transfer and aborted decarboxylation. The electronic nature of the Si surface changes character along the Si path due to two avoided crossings between jSi and S2 The first one occurs between the covalent state and the ionic La state along the reaction coordinate that interconverts the i9i-Min and. Si-Exc minima. The second one occurs between the ionic La state and the biradical Bi, state along the tautomerization coordinate that leads to the excited-state tautomerized form S -Taut. This point does not corresponds to a minimum on the potential-energy surface and it is found that evolution along a decarboxylation coordinate leads to a -Si /-So conical intersection, where efficient radiationless decay to the ground state takes place. The values of the relevant structural parameters are given in A. Data from Ref. 102.

Since tryptophan is also a fluorescence molecule, we monitored the disassembly through spectroscopic measurements. It was found that within the AB6 dendron (32), the tryptophan fluorescence was significantly quenched due to the confined proximity, which is forced by the dendritic skeleton. Upon the disassembly, we observed a gradual increase of two bands on 400 and 760 nm that correspond to free tryptophan molecules (Fig. 5.28). 

Marme N, Knemeyer JP, Sauer M, Wolfram J (2003) Inter- and intramolecular fluorescence quenching of organic dyes by tryptophan. Bioconjug Chem 14 1133-1139... 

Muino PL, Callis PR (2009) Solvent effects on the fluorescence quenching of tryptophan by amides via electron transfer. Experimental and computational studies. J Phys Chem B 113 2572-2577... 

Chen J, Callis PR, King J (2009) Mechanism of the very efficient quenching of tryptophan fluorescence in human gamma D- and gamma S-crystallins the gamma-crystallin fold may have evolved to protect tryptophan residues from ultraviolet photodamage. Biochemistry 48(17) 3708-3716... 

Callis PR, Liu T (2006) Short range photoinduced electron transfer in proteins QM-MM simulations of tryptophan and flavin fluorescence quenching in proteins. Chem Phys 326 (l) 230-239... 

Qiu W, Li T, Zhang L, Yang Y, Kao Y-T, Wang L, Zhong D (2008) Ultrafast quenching of tryptophan fluorescence in proteins interresidue and intrahelical electron transfer. Chem Phys 350 154-164... 

Rachel, K., Asuncionpunzalan, E. and London, E. (1995) Anchoring of tryptophan and tyrosine analogs at the hydrocarbon polar boundary in model membrane-vesicles - paralax analysis of fluorescence quenching induced by nitroxide-labelled phospholipids. Biochemistry 34,15475-15479. 

S. S. Lehrer, Solute perturbation of protein fluorescence. The quenching of other tryptophan fluorescence of model compounds and of lysosome by iodide ion, Biochemistry 10, 3254-3263 (1971). 

A protein induced after coliphage N4 infection has been studied. Although it has one or two tryptophans, its intrinsic fluorescence is dominated by the ten tyrosines/1111 Tryptophan fluorescence is seen after denaturing the protein. Upon binding to single-stranded DNA, the tyrosine fluorescence is quenched. This signal has been used to demonstrate that the binding affinity is very dependent on salt concentration and is also very sensitive to the nucleotide sequence. 

R. W. Wijnaendts van Resandt, Picosecond transient effect in the fluorescence quenching of tryptophan, Chem. Rhys. Lett. 95, 205-208 (1983). 

M. R. Eftink and K. A. Hagaman, Fluorescence quenching of the buried tryptophan residue of cod parvalbumin, Biophys. Chem. 22, 173-180 (1985). 

F. Tanaka and N. Mataga, Fluorescence quenching dynamics of tryptophan in proteins. Effect of internal rotation under potential barrier, Biophys. J. 51, 487-495 (1987). 

Fluorescence quenching has proven to be a powerful means to determine location of tryptophans. Small organic molecules, such as acetone, acrylamide, and amino acids, have been used to quench fluorescence of tryptophans which are exposed to the solvent.(50 51) These molecules apparently quench by close interaction and so provide a tool to determine the surface accessibility7 of tryptophan in a protein. 

Fig. 1.14 (a) The pH dependence of the rate constants for the association of carbonic anhydrase B (E) and p-nitrobenzenesnlfonamide (S). The reaction is monitored by nsing stopped-flow and the quenching of a tryptophan fluorescence in the protein which occurs when sulfonamides bind. The full line fits Eqn. (1.226) with k = 3.5 X lO M- s-, pA g = 7.5 and pK =... 

---