Elucidation of the local dynamics of domain-III of human serum albumin over the ps–μs time regime using a new fluorescent label

Abstract

The ps-μs dynamics of domain-III of human serum albumin (HSA) has been investigated using a new fluorescent marker selectively labeled to the Tyr-411 residue. The location of the marker has been confirmed using Förster resonance energy transfer (FRET) study. Steady state, time-resolved and single molecular level fluorescence techniques have been employed to understand the dynamics within the domain-III of HSA. It is found that solvent reorganization dynamics in domain-III is 1.7 times faster than that in domain-I. The timescale of the local rotational dynamics of domain-III is found to be 2.3 times faster than that of domain-I. Fluorescence correlation spectroscopic experiments reveal that domain-III of HSA has more conformational flexibility than domain-I. Together, the results deliver useful details of the local environment around the domain-III of HSA, which have not been explored earlier, mainly because of a lack of a suitable fluorescent marker for domain-III. The newly synthesized probe serves well as a site specific fluorescent marker for HSA, and can be used for further investigation of the ligand binding properties and enzymatic activity of domain-III of HSA.

Region-Specific Double Denaturation of Human Serum Albumin: Combined Effects of Temperature and GnHCl on Structural and Dynamical Responses

“…The helicity of the native state of HSA has been calculated as 64.2%, which is in good agreement with the reported value. 38,39…”

“…Domain-I of HSA has a single free cysteine residue at the 34th position, which can be tagged with thiol-specific fluorescence probes. 32,33,38,39 In our earlier reports, we have labeled domain-I with tetramethylrhodamine-5-maleimide and N -(7-dimethylamino-4-methylcoumarin-3-yl)iodoacetamide (DACIA). 38 Domain-III, on the other hand, has a tyrosine residue at the 411th position, which is much more active than the other tyrosine residues and can be selectively labeled by hydroxyl-specific fluorescent probes.…”

“…In one of our recent reports, we have designed and synthesized a fluorescent marker p -nitrophenyl coumarin ester (NPCE), which successfully tags Tyr-411 and delivers useful domain-specific information. 39…”

Enhanced Luminescent Properties of Photo‐Stable Copper Nanoclusters through Formation of “Protein‐Corona”‐Like Assemblies

“…Fluorescence correlation spectroscopy (FCS) has been established to be a highly sensitive technique to study molecular level diffusion and kinetics of the self‐assembled systems ,,. Diffusion studies were carried out using FCS technique by adjusting the solution concentration of CuNCs to nanomolar regimes .…”

Study on the molecular recognition action of lamivudine by human serum albumin

“…The fluorescence spectra of HSA exhibited no abnormality when 3TC was added, which was a sign that nonradiative energy transfer had taken place. According to Förster's nonradiative fluorescence resonance energy transfer (FRET) theory, the energy transfer can occur only when the fluorescence emission spectra of the donor and the absorption spectra of the acceptor have enough overlap and the distance between donor and acceptor is less than 8 nm. The FRET efficiency E can be described by the equation: where r is the distance between the acceptor and the donor and R 0 is the distance at which 50% of the energy is transferred and can be calculated by the equation: where K 2 denotes the space factor of orientation, N is the refractive index of medium; ф is the fluorescence quantum yield of the donor, and J represents the effect of the spectral overlap between the emission spectrum of the donor and the absorption spectrum of the acceptor (Figure ), which can be obtained by integrating the overlap spectra according to the equation: where F D ( λ ) is the corrected fluorescence intensity of the donor in the wavelength range from λ 0 to λ and ε A ( λ 0 ) is the extinction coefficient of the acceptor at λ 0 .…”