Femtosecond studies of protein–ligand hydrophobic binding and dynamics: Human serum albumin

Zhong, Dongping; Douhal, Abderrazzak; Zewail, Ahmed H.

doi:10.1073/pnas.250491297

Cited by 183 publications

(216 citation statements)

References 27 publications

(4 reference statements)

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“…Because of CD and HSA confinement, the time scale for the C-N and C-C coupling may change when compared with that in free OII; the space restriction makes the twisting͞rotation channel less favorable, and, therefore, the trans isomer may take longer time to enter the isomerization region, and thus the phenyl inversion occurs. This kind of delay in reactivity due to nanocavity restriction of nuclear rearrangement has been observed in a molecule showing IPT and twisting motion at S 1 (4,8,9).…”

Section: Femtochemistry In Solutionmentioning

confidence: 61%

“…Therefore, simple and complex (in concept) molecular systems have been studied using cyclodextrins (CDs), proteins, micelles, pores, and zeolites as nanohosts, demonstrating the confinement effect of the hydrophobic nanocavities on the spectroscopy and dynamics of the guests (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Relevant information on the ultrafast dynamics of caged wavepackets involving breaking͞making chemical bonds, and solvation has been acquired.…”

mentioning

confidence: 99%

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Femtochemistry of orange II in solution and in chemical and biological nanocavities

Douhal

Sanz

Tormo

2005

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

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In this work, we report on studies of the nature of the dynamics and hydrophobic binding in cyclodextrins and human serum albumin protein complexes with orange II. With femtosecond time resolution, we examined the proton-transfer and trans-cis isomerization reactions of the ligand in these nanocavities and in pure solvents. Because of confinement at the ground state, the orientational motion in the formed phototautomer is restricted, leading to a rich dynamics. Therefore, the emission lifetimes span a large window of tens to hundreds of picoseconds in the cavities. Possible H-bond interactions between the guest and cyclodextrin do not affect the caged dynamics. For the protein-ligand complexes, slow diffusional motion (Ϸ630 ps) observed in the anisotropy decay indicates that the binding structure is not completely rigid, and the embedded guest is not frozen with the hydrophobic pocket. The ultrafast isomerization and decays are explained in terms of coupling motions between N-N and C-N stretching modes of the formed tautomer. We discuss the role of confinement on the trans-cis isomerization with the cavities and its relationships to frequency and time domains of nanostructure emission.cyclodextrins ͉ protein ͉ H-bond ͉ twisting ͉ anisotropy F emtosecond (fs) studies of caged molecules in nanocavities provide direct information on the relationship between time and space domains of molecular relaxation (1). Therefore, simple and complex (in concept) molecular systems have been studied using cyclodextrins (CDs), proteins, micelles, pores, and zeolites as nanohosts, demonstrating the confinement effect of the hydrophobic nanocavities on the spectroscopy and dynamics of the guests (2-13). Relevant information on the ultrafast dynamics of caged wavepackets involving breaking͞making chemical bonds, and solvation has been acquired.Orange II (OII) (Fig. 1), also called acid orange 7, is a molecule that has O-H . . . N and NAN bonds and may show photoinduced intramolecular proton-transfer (IPT) and transcis isomerization reactions. It is widely used in the dyeing of textiles, food, and cosmetics and thus is found in the wastewaters of the related industries (14). It has been reported that it exists under azoenol (AZO) and ketohydrazone (HYZ) forms (Fig. 1) (15-20). In a water solution, for example, the H-atom within the O-H . . . N intramolecular H-bond is shifted to the nitrogen site, making HYZ structure the most stable one (Ϸ95%) (20). In DMSO, the HYZ population decreases to 70%, and in solid state it becomes the only populated structure (20). Recent x-ray studies of phenyl substituted 1-(arylazo)-2-naphthols showed that this kind of molecules displaying HYZ-AZO tautomerism can form intramolecular resonance-assisted H-bonds from pure N-H . . . O to pure N . . . H-O structures, depending on the phenyl derivative (21, 22). Furthermore, a recent photophysical study of similar molecules in solution has shown the occurrence of a photoinduced proton-transfer reaction in AZO to give HYZ structure with a very low emission qu...

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Section: Femtochemistry In Solutionmentioning

confidence: 61%

mentioning

confidence: 99%

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Douhal

Sanz

Tormo

2005

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

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“…It is expected because at pH 2.0, cyt c carries a net positive charge and ANS carries one unit of negative charge. However, other non-covalent interactions such as hydrophobic, van der Waals and hydrogen bonding also contribute to the effective free energy of the protein-ligand complexation [37]. Due to the increased surface hydrophobicity of the MG-state compared to that in the N-state, the former can bind the non-polar molecules in solution more strongly.…”

Section: Temperature Dependence Of the Binding Of Ans To The A-state Ofmentioning

confidence: 99%

Thermodynamic insights into the binding of ANS with the salt induced molten globule states of cytochrome c

Sharma

Kishore

2009

The Journal of Chemical Thermodynamics

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“…These dynamics involve local constrained protein and trapped-water motions within angstrom distance and occur on ultrafast time scales (6,7,10,11). Typically, extrinsic dye molecules or synthetic amino acids were used as local optical probes to label function sites, and the local relaxations were observed, ranging from femtoseconds to nanoseconds (5,(12)(13)(14).…”

mentioning

confidence: 99%

Ultrafast solvation dynamics at binding and active sites of photolyases

Chang

Guo

Kao

et al. 2010

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

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Dynamic solvation at binding and active sites is critical to protein recognition and enzyme catalysis. We report here the complete characterization of ultrafast solvation dynamics at the recognition site of photoantenna molecule and at the active site of cofactor/ substrate in enzyme photolyase by examining femtosecondresolved fluorescence dynamics and the entire emission spectra. With direct use of intrinsic antenna and cofactor chromophores, we observed the local environment relaxation on the time scales from a few picoseconds to nearly a nanosecond. Unlike conventional solvation where the Stokes shift is apparent, we observed obvious spectral shape changes with the minor, small, and large spectral shifts in three function sites. These emission profile changes directly reflect the modulation of chromophore's excited states by locally constrained protein and trapped-water collective motions. Such heterogeneous dynamics continuously tune local configurations to optimize photolyase's function through resonance energy transfer from the antenna to the cofactor for energy efficiency and then electron transfer between the cofactor and the substrate for repair of damaged DNA. Such unusual solvation and synergetic dynamics should be general in function sites of proteins.function-site solvation | ultrafast dynamics | spectral tuning | protein rigidity and flexibility | femtosecond-resolved emission spectra D ynamic solvation in binding and active sites plays a critical role in protein recognition and enzyme reaction, and such local motions optimize spatial configurations and minimize energetic pathways (1-11). These dynamics involve local constrained protein and trapped-water motions within angstrom distance and occur on ultrafast time scales (6,7,10,11). Typically, extrinsic dye molecules or synthetic amino acids were used as local optical probes to label function sites, and the local relaxations were observed, ranging from femtoseconds to nanoseconds (5,(12)(13)(14). Such labeling of bulky dye molecules usually induces significant local perturbations, and direct characterization with intrinsic chromophores in proteins eliminates those interferences and reveals intact environment responses (4, 7, 15-21), as recently examined in green fluorescence proteins (21). We have recently studied a series of flavoproteins using intrinsic flavin molecule as the optical probe (10, 22, 23) and especially found the important functional role of local solvation in photolyase (10).Photolyase, a flavoprotein and a photoenzyme, repairs damaged DNA caused by UV irradiation. Two types of structurally similar photolyases are specific for two major UV-induced DNA lesions of cyclobutane pyrimidine dimer (CPD) and (6-4) photoproduct (24). The CPD photolyase contains two noncovalently bound chromophores, a pterin molecule in the form of methenyltetrahydrofolate (MTHF) in the binding site as the photoantenna for energy efficiency and a fully reduced flavin adenine dinucleotide (FADH − ) at the active site as the catalytic cofactor for repair of d...

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Femtosecond studies of protein–ligand hydrophobic binding and dynamics: Human serum albumin

Cited by 183 publications

References 27 publications

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Femtochemistry of orange II in solution and in chemical and biological nanocavities

Thermodynamic insights into the binding of ANS with the salt induced molten globule states of cytochrome c

Ultrafast solvation dynamics at binding and active sites of photolyases

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