Decay associated fluorescence spectra of coumarin 1 and coumarin 102: evidence for a two-state solvation kinetics in organic solvents

Yip, R. W.; Wen, Yang; Szabo, Arthur G.

doi:10.1021/j100142a032

Cited by 46 publications

(53 citation statements)

References 5 publications

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“…So the absorption spec- tra are redshifted in polar solvents, as seen in the TDDFT results and experimental results. 8,10,[13][14][15] The main contributors to the HOMO are the N13 and the benzene ring. In comparison with the HOMO, the LUMO is more localized on the C2¼ ¼O11 and C4¼ ¼C3H groups.…”

Section: Resultsmentioning

confidence: 99%

“…C102 shows a large change in dipole moment on excitation and its absorption and emission spectra are very sensitive to solvent polarity. 8,10,[13][14][15] The amino group of C102 is tethered to the benzene moiety by two propylidene bridges (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…From this point of view, C102 is a nearly ideal probe in studying solvatochromic properties and characteristics of the solutesolvent interaction. So, it is not surprising that many experimental 8,10,[13][14][15][16][17][18][19] and theoretical [20][21][22][23][24] investigations on C102 have been reported. The experimental results of Moog et al suggested that except the influence of the solvent polarity, the extent of HB viewed as an influence on the electronic transition was conspicuous for C102 and the Kamlet-Taft equation was used to investigate solvatochromic properties.…”

Section: Introductionmentioning

confidence: 99%

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Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

Zhao

Xia

2010

J Comput Chem

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The effect of both solvent polarity and hydrogen bonding (HB) on the electronic transition energy of Coumarin 102 (C102) has been examined using the time-dependent density functional theory (TDDFT). Solvent effect on both geometry and electronic transition energy is evaluated using the polarizable continuum model (PCM). A linear relation of the absorption maximum of C102 with the solvent polarity function Δf is found using the TDDFT-PCM method for all solvents except dimethyl sulfoxide. The solvent polarity and the type B HB between the carbonyl oxygen and solvent hydrogen atom make the absorption wavelength redshift, whereas the type A HB between the amino nitrogen atom and solvent hydrogen atom has an opposite effect on the absorption wavelength. The calculated absorption wavelengths of C102 with two type B HB between the carbonyl oxygen and solvent hydrogen atom are in excellent agreement with experimental measurements. The solvatochromism of C102 is analyzed in terms of the Kamlet-Taft equation and the parameters s and a are discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

Zhao

Xia

2010

J Comput Chem

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“…The decay-associated emission spectra of tryptophan fluorescence of P-450,,, were computed from the use of the steady-state emission spectra Z(A) and the fluorescence-decay parameters, a, and t, (Robbins et al, 1985;Yip et al, 1993). The intensity Z,(A) due to the component i at particular wavelength, A, can be given as…”

Section: The Observed Fluorescence-decay Data [F(t)] Is a Convolutimentioning

confidence: 99%

Steady‐State and Picosecond‐Time‐Resolved Fluorenscence Studies on the Recombinant Heme Domain of Bacillus megaterium Cytochrome P‐450

Khan

Mazumdar

Modi

et al. 1997

European Journal of Biochemistry

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The conformational changes associated with the interaction of sodium laurate with the recombinant heme domain for cytochrome P-450BM3 have been investigated by steady-state and picosecond-timeresolved fluorescence spectroscopy. The steady-state quenching experiments show that while all the five tryptophan residues are accessible to acrylamide in the free enzyme as well as the enzyme . substrate complex, the number of tryptophan residues accessible to ionic quenchers decreases on interaction of the substrate with the enzyme. This indicates that some of the tryptophan residues move towards the core of the protein on interaction with the substrate. The number of tryptophan residues accessible to the solvent as determined by the calculation of the solvent-accessible area for the free enzyme agrees with the values obtained by the quenching experiments.The time-resolved fluorescence studies carried out by means of the time-correlated single-photoncounting technique show that the fluorescence-decay curve is best fitted to a three-exponential model (0.2, 1.0 and 5.4 ns). Lifetime distributions, as recovered by the maximum-entropy method, agree with the discrete exponential model. The binding of the substrate does not lead to any significant change in the lifetime components of the enzyme, indicating that the tryptophan residues are possibly away from the substrate-binding domain. The decay-associated emission spectra and the magnitudes of amplitude of different lifetimes indicate that the shortest lifetime component ( 7 , ) originates from the three tryptophan residues that are completely or partially accessible to the solvent, and t, originates from the tryptophan residues that are buried in the core of the enzyme and not accessible to the solvent. X-ray crystallographic data and solvent-acessible-area calculations have been used to identify these residues.

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“…Decay-associated Spectra-The decay-associated emission spectra were computed from steady-state emission spectrum and fluorescence decay parameters (23,24), as shown by Equation 7,…”

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confidence: 99%

Interaction of 7-Hydroxy-8-(phenylazo)1,3-naphthalenedisulfonate with Bovine Plasma Albumin

Patel

Srivastava

Phadke

1999

Journal of Biological Chemistry

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Sulfonated compounds have been used as biological staining reagents for some time. However, only recently it has been realized that some of these compounds can exhibit diverse biological activities (1-5) and hence are looked upon as potential pharmaceutical agents and important lead compounds (6 -8). The effectiveness of these compounds as pharmaceutical agents depends on their ability to reach and bind to the specific sites on the target proteins. Albumins are the principal proteins found in plasma contributing to the colloid osmotic pressure of the blood and also act as transport proteins for numerous endogenous and exogenous compounds (9). These have propensity to bind a wide variety of ligands. Because of this, albumins are assumed to function as transport protein and possibly serve as vehicles for regulating levels of drugs and metabolites in blood (10).The mode of interaction of various sulfonated azo compounds including 7-hydroxy-8-(phenylazo)1,3-naphthelenedisulfonate, commonly known as Orange G (OG) 1 (Fig. 1B) with amino acids such as Arg, Lys, and His has been reported (11). To the best of our knowledge, there is no report on the interaction of OG with any protein. Detailed knowledge of the OG-albumin interaction is relevant to the understanding of interaction of sulfonated azo dyes with enzymes and with specific binding proteins. We have therefore undertaken detailed investigations on the mode of interaction of OG and plasma protein called bovine plasma albumin (BPA).In this report, we have characterized BPA⅐OG complex using a variety of spectroscopic techniques such as nuclear magnetic resonance (NMR), circular dichroism (CD), fluorescence, etc. In addition, the conformation of BPA and of OG in BPA⅐OG complex is discussed. EXPERIMENTAL PROCEDURESMaterials-Bovine plasma albumin was purchased from Armour Pharmaceutical Co. and Orange G from Sigma. Concentration of BPA was determined using molecular mass of 66 kDa and A 279 ϭ 0.667 mg Ϫ1 ml cm Ϫ1 (12) and that of OG using ⑀ 478 ϭ 19900 M Ϫ1 cm Ϫ1. Other chemicals used were of AnalaR grade. 20 mM phosphate buffer, pH 7.2, was used. A mixture of acetate and phosphate (20 mM) was used to obtain pH in the range 4 -8.NMR-NMR measurements were carried out on a Varian Unity Plus 600-MHz spectrometer. Chemical shifts were measured with respect to sodium trimethylsilyl-propionate-2,2,3,3-d 4 . One-dimensional spectra were recorded with 16,000 data points, 6499-Hz spectral width, 64 transients, and a 2-s relaxation delay at 25°C. A 200-ms mixing time was used in the nuclear Overhauser effect spectroscopy (NOESY) (13) experiment. For 13 C-T 1 measurements, inversion recovery pulse sequence was incorporated in gradient enhanced heteronuclear single quantum coherence spectroscopy sequence (14). A relaxation time of 3 s was used. The 1 H spin lattice relaxation times (T 1 ) were measured using inversion recovery pulse sequence (15) using 12-s relaxation delay. The solvent resonance was suppressed by irradiation during relaxation delay and recovery time. T 1 was calc...

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Decay associated fluorescence spectra of coumarin 1 and coumarin 102: evidence for a two-state solvation kinetics in organic solvents

Cited by 46 publications

References 5 publications

Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

Steady‐State and Picosecond‐Time‐Resolved Fluorenscence Studies on the Recombinant Heme Domain of Bacillus megaterium Cytochrome P‐450

Interaction of 7-Hydroxy-8-(phenylazo)1,3-naphthalenedisulfonate with Bovine Plasma Albumin

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