Photochemistry of the model phototropic system involving flavines and indoles. III. A spectroscopic study of the polarized luminescence of indoles

Song, Pill‐Soon; Kurtin, William E.

doi:10.1021/ja01045a052

Cited by 150 publications

(46 citation statements)

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“…50 Indole, however, is believed to have two closely spaced electronic states, which are 1 L a and 1 L b . 51 The relative energies of these two states are extremely sensitive to the nature of the solvent. 52 Several semiempirical calculations have suggested that the lowest electronic state of indole in the gas phase is the 1 L b state, and the transition moment for this state has been calculated to lie anywhere between 25°and 88°from the A-axis ( Figure 5) in the plane of the molecule.…”

Section: Resultsmentioning

confidence: 99%

Characterization of the Tryptophan Residues of Human Placental Ribonuclease Inhibitor and Its Complex with Bovine Pancreatic Ribonuclease A by Steady-State and Time-Resolved Emission Spectroscopy

et al. 2006

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Human placental ribonuclease inhibitor (hRI) containing six tryptophan (Trp) residues located at positions 19, 261, 263, 318, 375, and 438 and its complex with RNase A have been studied using steady-state and time-resolved fluorescence (298 K) as well as low-temperature phosphorescence (77 K). Two Trp residues in wild-type hRI and also in the protein-protein complex with RNase A are resolved optically. The accessible surface area values of Trp residues in the wild-type hRI and its complex and consideration of inter-Trp energy transfer in the wild-type hRI reveal that one of the Trp residues is Trp19, which is located in a hydrophobic buried region. The other Trp residue is tentatively assigned as Trp375 based on experimental results on wild-type hRI and its complex. This residue in the wild-type hRI is more or less solvent exposed. Both the Trp residues are perturbed slightly on complex formation. Trp19 moves slightly toward a more hydrophobic region, and the environment of Trp375 becomes less solvent exposed. The complex formation also results in a more heterogeneous environment for both the optically resolved Trp residues.

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Section: Resultsmentioning

confidence: 99%

Characterization of the Tryptophan Residues of Human Placental Ribonuclease Inhibitor and Its Complex with Bovine Pancreatic Ribonuclease A by Steady-State and Time-Resolved Emission Spectroscopy

et al. 2006

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“…Information about the direction of the transition moment in tryptophan comes from crystal absorption spectra of indole derivatives (21) and theoretical calculations (21,44,45 (6) and torsion angle (O) that result from such a rotation. Fig.…”

Section: Discussionmentioning

confidence: 99%

Picosecond fluorescence decay of tryptophans in myoglobin.

Hochstrasser¹,

Negus²

1984

Proc. Natl. Acad. Sci. U.S.A.

122

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The fluorescence decay characteristics of Mb, MbCO, metMb (sperm whale), metMb (yellowfin tuna), and their apo derivatives were determined by using a picosecond streak camera and time-correlated single photon counting. The emission is dominated by tryptophans that transfer their energy to the heme on a subnanosecond time scale. Sperm whale Mb and derivatives have two tryptophans and their decays can be interpreted mainly as two exponentials, one of ca. 20 ps and the other of 130 ps, whereas tuna Mb has one tryptophan and its emission is nonexponential but dominated by one component of 31 ps. These results along with F6rster energy transfer calculations allow us to assign the ca. 30-ps emission to Trp-14 and the 130-ps emission to Mb. The streak camera was modified to determine the decay of the fluorescence anisotropy. In metMb (tuna) the fluorescence anisotropy decays in 100 ps, which is postulated to result from rapid motion of the Trp-14. Because energy transfer was used to gate the anisotropy, the fast motion of Trp-14 is proposed to correspond to only 10% of the equilibrium distribution of molecules.Tryptophans are useful optical probes of protein structure because of their relatively long wavelength absorption compared with polypeptides and other common amino acid residues. A first step in realizing the full potential of such probes is the development of techniques to distinguish the different tryptophans in a protein by means of their optical responses. We have therefore carried out picosecond laser experiments on Mb aimed at characterizing the fluorescent behavior of each of the tryptophans. Previous picosecond laser experiments aimed at detecting rapid conformational changes and relaxation processes in heme proteins have involved studying changes in the heme electronic structure as a result of photodeligation of CO (1-6), 02 (1,(4)(5)(6), and NO (6, 7). A goal of the present research is to pave the way for the study of the transmission of structural changes throughout the protein, and as a first step we have attempted in the present work to chart the picosecond anatomy of the tryptophans of Mb.Pulsed laser techniques are needed to study tryptophan fluorescence in heme proteins as a result of very efficient energy transfer to the heme. The low fluorescence quantum yields for tryptophan in heme proteins (8) suggest that the corresponding lifetimes are in the picosecond range. Thus, to obtain direct information on the lifetimes and motional characteristics of such tryptophans it was necessary to devise experiments by which the fluorescence and its polarization could be measured with picosecond accuracy.Sperm whale (SW) Mb is known to contain the two tryptophan residues, Trp-7 and Trp-14 (9). Thus, it is expected that the emission will be dominated by two decays. The heme is considerably further from Trp-7 than from Trp-14 (20 A compared with 15 A) so that the effects of energy transfer on these excited states are expected to be different. Tuna Mb has an x-ray structure very similar to SW Mb (10) bu...

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“…The cause of the apparent reduction of the initial anisotropy is not known. Suggested explanations include mixing of 'La and 'Lb transitions in either absorption (Valeur & Weber, 1977) or emission (Song & Kurtin, 1969) and changes in the direction of the dipole moment of the 'La excited state due to interaction with the solvent (Sun & Song, 1977), to exciplex formation (Walker et al, 1967), or to torsional vibrations (Jablonski, 1965). We treat some of these possibilities in the following section.…”

Section: )E-t/rl + P]e-'/7mmentioning

confidence: 99%

Fluorescence depolarization of tryptophan residues in proteins: a molecular dynamics study

Ichiye¹,

Karplus²

1983

Biochemistry

156

104

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A molecular dynamics simulation of lysozyme is used to examine the fluorescence depolarization of tryptophan residues on the picosecond time scale. The calculated time dependence of fluorescence emission anisotropy for the six tryptophans in lysozyme exhibits a wide variety of motional behavior that should correspond to the range expected more generally for tryptophan residues in proteins. It is found that some tryptophans are highly mobile with a large fluorescence anisotropy decay on the picosecond time scale while others are essentially rigid due to the presence of the protein matrix. Further, it is demonstrated that correlations among the internal degrees of freedom (e.g., dihedral angles) play an important role in the observed decay behavior; this suggests that care has to be used in interpreting experimental results in terms of simple motional models. Because the available experimental time resolution is limited to the nanosecond time scale, only the effective zero-time anisotropy can be compared with the calculated values. The results suggest that the study of fluorescence depolarization with femtosecond lasers would provide new insights into the short time dynamics of amino acid side chains in proteins.

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Photochemistry of the model phototropic system involving flavines and indoles. III. A spectroscopic study of the polarized luminescence of indoles

Cited by 150 publications

References 4 publications

Characterization of the Tryptophan Residues of Human Placental Ribonuclease Inhibitor and Its Complex with Bovine Pancreatic Ribonuclease A by Steady-State and Time-Resolved Emission Spectroscopy

Characterization of the Tryptophan Residues of Human Placental Ribonuclease Inhibitor and Its Complex with Bovine Pancreatic Ribonuclease A by Steady-State and Time-Resolved Emission Spectroscopy

Picosecond fluorescence decay of tryptophans in myoglobin.

Fluorescence depolarization of tryptophan residues in proteins: a molecular dynamics study

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