Nonexponential fluorescence decay of tryptophan, tryptophylglycine, and glycyltryptophan

Chang, Mu‐Chieh; Petrich, Jacob W.; McDonald, Daniel B.; Fleming, Graham R.

doi:10.1021/ja00350a013

Cited by 163 publications

(110 citation statements)

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“…When the ~L a state is excited at 300 nm, the fluorescence light is emitted in the range 330-360 nm. Hence, for these excitation and emission wavelengths one lifetime of the tryptophan fluorescence is expected and this is indeed found in some cases, the most notable one being N-acetyltryptophanamide (NATA) with a lifetime of about 3 ns (Szabo and Rayner 1980;Wijnaendts van Resandt et al 1980;Robbins et al 1980;Ross et al 1981;Chang et al 1983;Wagner et al 1987;Bismuto et al 1991;Vekshin et al 1992). However, the amino acid tryptophan already exhibits two lifetimes (at neutral pH).…”

Section: Introductionmentioning

confidence: 96%

A long lifetime component in the tryptophan fluorescence of some proteins

et al. 1995

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The tryptophan fluorescence of two membrane proteins (outer membrane protein A and lactose permease), a 21-residue hydrophobic peptide, three soluble proteins (rat serum albumin, ribonuclease T1, and azurin), and N-acetyltryptophanamide (NATA) was investigated by time-resolved measurements extended over 65 ns. A long lifetime component with a characteristic time of 25 ns and an amplitude below 1% was found for outer membrane protein A, lactose permease, the peptide in lipid membranes, and azurin in water, but not for rat serum albumin, ribonuclease T1, and NATA in water. When outer membrane protein A was dissolved and unfolded in guanidinum hydrochloride, the long lifetime component disappeared. Hence, a hydrophobic environment seems to be a necessary requirement for the long lifetime component to be present. However, NATA dissolved in butanol does not exhibit the long lifetime component, while the peptide dissolved in the same solvent under conditions which preserve its helical structure does show the long lifetime. Thus, a regular secondary structure for the polypeptide chain to which the tryptophan residue belongs seems to be a second necessary requirement for the long lifetime component to be present. The long lifetime component may therefore be seen in the context of protein substates.

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Section: Introductionmentioning

confidence: 96%

A long lifetime component in the tryptophan fluorescence of some proteins

et al. 1995

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“…The results are discussed with reference to the peculiar photophysics of tryptophan (Andrews and Forster 1974;Szabo and Rayner 1980;Chang et al 1983;Petrich et al 1983;Cross et al 1983;Ichiye and Karplus 1983;Creed 1984). Polarized fluorescence decay measurements were used to investigate the rotational motion of the tryptophans in both flavodoxins.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved fluorescence studies of flavodoxin. Fluorescence decay and fluorescence anisotropy decay of tryptophan in Desulfovibrio flavodoxins

et al. 1990

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The time-resolved fluorescence characteristics of tryptophan in flavodoxin isolated from the sulfate-reducing bacteria Desulfovibrio vulgaris and Desulfovibrio gigas have been examined. By comparing the results of protein preparations of normal and FMN-depleted flavodoxin, radiationless energy transfer from tryptophan to FMN has been demonstrated. Since the crystal structure of the D. vulgaris flavodoxin is known, transfer rate constants from the two excited states 1La and 1Lb can be calculated for both tryptophan residues (Trp 60 and Trp 140). Residue Trp 60, which is very close to the flavin, transfers energy very rapidly to FMN, whereas the rate of energy transfer from the remote Trp 140 to FMN is much smaller. Both tryptophan residues have the indole rings oriented in such a way that transfer will preferentially take place from the 1La excited state. The fluorescence decay of all protein preparations turned out to be complex, the parameter values being dependent on the emission wavelength. Several decay curves were analyzed globally using a model in which tryptophan is involved in some nanosecond relaxation process. A relaxation time of about 2 ns was found for both D. gigas apo- and holo-flavodoxin. The fluorescence anisotropy decay of both Desulfovibrio FMN-depleted flavodoxins is exponential, whereas that of the two holoproteins is clearly non-exponential. The anisotropy decay was analyzed using the same model as that applied for fluorescence decay. The tryptophan residues turned out to be immobilized in the protein. A time constant of a few nanoseconds results from energy transfer from tryptophan to flavin, at least for D. gigas flavodoxin. The single tryptophan residue in D. gigas flavodoxin occupies a position in the polypeptide chain remote from the flavin prosthetic group. Because of the close resemblance of steady-state and time-resolved fluorescence properties of tryptophan in both flavodoxins, the center to center distance between tryptophan and FMN in D. gigas flavodoxin is probably very similar to the distance between Trp 140 and FMN in D. vulgaris flavodoxin (i.e. 20 A).

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“…In aqueous solution, besides sub-ps photo-ionization [9-11] and intersystem crossing [12][13][14] at long times, the intermediate, nanosecond time scale is characterized by a multi-exponential fluorescence decay. The latter has been rationalized on the basis of different rotameric configurations [15], and is thought to involve an excited-state proton [15][16][17][18] or charge-transfer [19,20], eventually leading to a primary photoproduct whose spectroscopic signature has not been identified so far.Nanosecond photolysis studies have reported an absorption band (k peak = 400-440 nm, s $ 20-45 ns) -termed as 'T 1 ' [12][13][14], that could qualify for being the primary photoproduct's signature. It has been observed only in conditions in which Trp's side chain ammonium group is protonated (NH þ 3 ), which seems to be the key side chain group for S 1 quenching [17,20], but due to insufficient time-resolution, a direct correlation of its formation with the S 1 quenching time is lacking.…”

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confidence: 99%

“…In aqueous solution, besides sub-ps photo-ionization [9][10][11] and intersystem crossing [12][13][14] at long times, the intermediate, nanosecond time scale is characterized by a multi-exponential fluorescence decay. The latter has been rationalized on the basis of different rotameric configurations [15], and is thought to involve an excited-state proton [15][16][17][18] or charge-transfer [19,20], eventually leading to a primary photoproduct whose spectroscopic signature has not been identified so far.…”

mentioning

confidence: 99%