luminophore-formation-various-conformations-bovine-serum-albumin

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em ...

limited-proteolysis-gel-electrophoresis-presence-metal-cations-au-iii

Limited Proteolysis and Gel Electrophoresis in the Presence of Metal Cations: Au(III)-binding Luminescent Domain in Serum Albumins

The purpose of the presented protocols is to determine the domain of Au(III) binding in BSA. The BSA-Au(III) compound exhibits ultraviolet (UV)-excitable ...

University of North Carolina

The University of North Carolina

We report new findings on the red fluorescent (λ = 640 nm) bovine serum albumin (BSA)-gold (Au) compound initially described by Xie et al. (J. Am. Chem. Soc. 2009, 131, 888-889) as Au nanoclusters. The BSA-Au compounds were further reducible to yield nanoparticles, suggesting that these compounds were BSA-cationic Au complexes. We examined the correlations between BSA conformations (pH-induced as well as denatured) and the resulting fluorescence of BSA-Au complexes, to understand the possible cationic Au binding sites. The red fluorescence of the BSA-Au complex was associated with a particular isoform of BSA, the aged form (pH > 10) of the five pH-dependent BSA conformations, while the other conformations, expanded (pH < 2.7), fast (2.7 < pH < 4.3), normal (4.3 < pH < 8), and basic (8 < pH < 10) did not result in red fluorescence. There could be internal energy transfer mechanisms to produce red fluorescence, deduced from excitation-emission map measurements. The ensemble minimum number of Au(III) per BSA to yield red fluorescence was <7. We illustrate the presence of multiple specific Au binding sites in BSA, and present an interpretation of the fluorescence of the BSA-Au complex, alternative to a single-site nucleation of a neutral Au nanocluster.

Conformational Change-Induced Fluorescence of Bovine Serum Albumin-Gold Complexes.

Using the methods of equilibrium and non-equilibrium molecular dynamics alongside capillary viscometer experiments, we explore differences between united and all-atom models of a series of linear ethers. The models are based on two transferable force fields, and changes in viscosity and diffusion are studied across a wide range of temperatures and shear rates. We analyze diffusivity and viscosity data by means of the rotational relaxation time and Arrhenius equation. Rotational relaxation times are calculated explicitly from the ether chain's end-to-end vectors, and self-diffusion values are calculated from the mean square displacement. We find an increase in orientational alignment as temperature drops in both models and consistent differences in activation energies across the models and experiment. A clear relationship is observed between viscosity, rotational relaxation time, and diffusion time. These time constants also impact the reliability of the viscosity value determined by the Green-Kubo method. We also study the trends in zero-shear viscosity as chain length increases and force field performance relative to experiment as this length changes.

Shunji Egusa

Department of Physics and Optical Science,
Center for Biomedical Engineering & Science,
Department of Physics and Optical Science, Center for Biomedical Engineering & Science

University of North Carolina

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

Limited Proteolysis and Gel Electrophoresis in the Presence of Metal Cations: Au(III)-binding Luminescent Domain in Serum Albumins

Shunji Egusa

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Physics and Optical Science,Center for Biomedical Engineering & Science,Department of Physics and Optical Science, Center for Biomedical Engineering & Science

University of North Carolina

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

Limited Proteolysis and Gel Electrophoresis in the Presence of Metal Cations: Au(III)-binding Luminescent Domain in Serum Albumins

Department of Physics and Optical Science,
Center for Biomedical Engineering & Science,
Department of Physics and Optical Science, Center for Biomedical Engineering & Science