Polarized Absorption Spectra of Crystals of Indole and Its Related Compounds

Yamamoto, Yukio; Tanaka, Jirō

doi:10.1246/bcsj.45.1362

Cited by 173 publications

(104 citation statements)

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“…The radiative lifetime for tryptophan was estimated to be 20 ns from the fluorescence lifetime and fluorescence yield measured for apoMb (16). The direction of the tryptophan emission dipole was used as reported by Yamamoto and Tanaka (21 If all of the proteins in the sample were to maintain identical structures throughout the time scale of the fluorescence process, the energy transfer limited decay would be exponential for both tryptophans, thus double and single exponential decays would be expected for the SW and tuna Mb, respectively. In the present case the existence of many different fixed structures would give rise to nonexponential decay if the variance of the distribution of kis was sufficiently large.…”

Section: Discussionmentioning

confidence: 99%

“…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%

“…The time evolution of the fluorescence anistropy can yield important information about the molecular motion, but the analysis of tryptophan fluorescence requires consideration of the complexities of its photophysics (15-18). Two electronic states having differently oriented transition dipoles are involved in the absorption process (19)(20)(21)(22), and frequently there were observed two fluorescent states (15,17,23,24). …”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Picosecond fluorescence decay of tryptophans in myoglobin.

Hochstrasser¹,

Negus²

1984

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

122

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“…There have been several band decomposition studies in the UV absorption region that have been carried out on crystalline indole 60 as well as indole in propylene glycol glass 49,61,62 and polymer films. 63 On the basis of this data, we are confidently able to assume that, at 249 nm, we are exciting almost exclusively to the 1 L a state (even given the small shifts in the relative and absolute positions of the 1 L a and 1 L b states in these solid media relative to the gas phase).…”

Section: A Indole At 249 Nmmentioning

confidence: 99%

Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

Livingstone¹,

Schalk²,

Boguslavskiy³

et al. 2011

The Journal of Chemical Physics

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Time-resolved photoelectron spectroscopy was used to obtain new information about the dynamics of electronic relaxation in gas-phase indole and 5-hydroxyindole following UV excitation with femtosecond laser pulses centred at 249 nm and 273 nm. Our analysis of the data was supported by ab initio calculations at the coupled cluster and complete-active-space self-consistent-field levels. The optically bright 1 L a and 1 L b electronic states of 1 ππ* character and spectroscopically dark and dissociative 1 πσ* states were all found to play a role in the overall relaxation process. In both molecules we conclude that the initially excited 1 L a state decays non-adiabatically on a sub 100 fs timescale via two competing pathways, populating either the subsequently long-lived 1 L b state or the 1 πσ* state localised along the N-H coordinate, which exhibits a lifetime on the order of 1 ps. In the case of 5-hydroxyindole, we conclude that the 1 πσ* state localised along the O-H coordinate plays little or no role in the relaxation dynamics at the two excitation wavelengths studied.

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“…We also made a few simulations of the situation in which a negative point charge (centroid of a carboxylate group) was in the plane of the indole, near C-7, and computed the electrostatic potential along the transition dipole (17,18). These simulations showed several changes in sign of the potential, and they also suggested that the conformations in which the carboxylate centroid assumes this location are…”

mentioning

confidence: 99%

On how a myosin tryptophan may be perturbed.

Bivin

Kubota²,

Pearlstein³

et al. 1993

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

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A weil-known indication that a nucleotide has bound to myosin Is the enhancement of the fluorescence of a speciflc tryptophan in the "subfragment 1" segment of the protein. Empirically the effect has been enormously useful in myosin enzymology. But beyond an early suggestion that it aries from a purine-tryptophan charge-transfer complex, the mechanism of the effect has not been considered. Here we consider the alternative that it arises from an Ionizable group (either another residue or the phosphate of the nucleotide) whose proimit to the tryptophan is altered by substrate bnding. We study this possibility by studying the interaction of an ionizable residue and tryptophan when both are incorporated in a diketopiperazine structure. The geometry of the ituation is inferred from molecular mehaics simulations. Unexpectedly, the best explanation seems to be that the field of the imposed charge, acting across space, affects events in the excited state of the indole.The perturbation of the absorbance (1) and emission (2) (8), but alternative explanations have not been considered. We undertook the present study, hoping to get clues about the aforementioned effect in myosin and, more generally, information about environmental effects on tryptophan. Our specific goal was to study the effect of a single charge positioned in a known relation to the indole ring, using a setup in which the sign and quantity of the charge (and to a limited extent the geometry of the arrangement) could be varied. We sought to accomplish this goal by using diketopiperazines constructed from. tryptophan and the L or D forms of amino acids such as histidine or aspartic acid, using appropriate molecular mechanical analysis to characterize the charge-indole relation. MATERIALS AND METHODSPreparation of the Diketopiperazines. The strategy followed was to prepare t-butoxycarbonyl (Boc)-protected amino acids, to couple these into linear dipeptide esters, and then to cyclize them and remove the protective groups.Boc-Trp and Boc-Asp(13-OBz) (where Bz = benzoyl) were prepared according to Morodes et al. (9). Glu(-OBz) OBz-The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. 6791TosOH and His-OMe*2HCl were prepared according to Zervas et al. (10) and Humphlett and Wilson (11), respectively. Linear protected dipeptide esters were prepared by the N,N'-dicyclohexylcarbodiimide/N-hydroxysuccinimide method (12). Dimethylformamide was the solvent for coupling. The products were purified from ethyl acetate petroleum ether, except Boc-L-Trp-L-His-OMe, which was purified from warm ethanol. In TLC, each of the products gave a single spot (ninhydrin negative) using the KI/toluidine reaction for detection (13). To prepare the diketopiperazines, a Boc group was removed by dissolving 10 mmol of Bocprotected dipeptide ester in 120 ml (240 ml for the histidinecontaining dipeptide) of 0.1 M HCl/96% formic acid...

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Polarized Absorption Spectra of Crystals of Indole and Its Related Compounds

Cited by 173 publications

References 11 publications

Picosecond fluorescence decay of tryptophans in myoglobin.

Picosecond fluorescence decay of tryptophans in myoglobin.

Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

On how a myosin tryptophan may be perturbed.

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