1/18/2024 0 Comments Glycerol water viscosity![]() Here, we labeled the OCP of Synechocystis with tetramethylrhodamine-maleimide (TMR) and obtained a photoactive OCP-TMR complex, the fluorescence of which was highly sensitive to the protein state, showing unprecedented contrast between the orange and red states and reflecting changes in protein conformation and the distances from TMR to the carotenoid throughout the photocycle. Despite clear recent progress, the detailed mechanism of the OCP photoconversion and associated photoprotection remains elusive. This is thought to involve a 12-Å translocation of the carotenoid cofactor and separation of the N-and C-terminal protein domains. Orange carotenoid protein (OCP), responsible for the photoprotection of the cyanobacterial photosynthetic apparatus under excessive light conditions, undergoes significant rearrangements upon photoconversion and transits from the stable orange to the signaling red state. Monitoring rotational diffusion of bioconjugated NRs using FCS might prove to be a useful tool for observing binding and conformational dynamics in biological systems. By titrating peptide-coated NRs with Bovine Serum Albumin (BSA) we monitored (nonspecific) binding through rotational diffusion and showed that D rot is an advantageous observable for monitoring binding. NRs fall in the size range where rotational diffusion can be monitored with higher sensitivity than translational diffusion due to a steeper length dependence D rot ~ L −3 versus D trans ~ L −1. Translational and rotational diffusion constants (D trans and D rot ) for NRs were in good agreement with Tirado and Garcia de la Torre's as well as with Broersma's theories, when accounting for the ligand dimensions. We monitored rotational and translational diffusion of NRs and extracted hydrodynamic radii from the extracted diffusion constants. Theoretical predictions of the NRs' rotational diffusion contribution to the correlation curves were experimentally confirmed. This conclusion was supported by the particular quality of the Brownian motion trajectories set in this cell as compared to the other three cells.ĬdSe/CdS/ZnS nanorods (NRs) of three aspect ratios were coated with phytochelatin-related peptides and studied using fluorescence correlation spectroscopy (FCS). The viscosity value of 11.3 ± 1.7 cP was supposed to be an overestimation, caused by the peculiarities of the vacuole structure and/or volume in this particular cell. The first three viscosity values correspond to 30-40% glycerol solutions. Apparent viscosity values in the vacuoles of the cells, computed by the Einstein-Smoluchowski equation using the obtained data, were found to be 2.16 ± 0.60, 2.52 ± 0.63, 3.32 ± 0.9 and 11.3 ± 1.7 cP. In four yeast cells, the 2D displacements and sizes of the IPCs were evaluated. On latex microspheres, a methodology was developed for measuring a fluorescing particle's two-dimensional (2D) displacements and its size. IPC movement was photorecorded and shown to be Brownian motion. ![]() cerevisiae cells stained by DAPI and fluorescein isothyocyanate-labelled latex microspheres, using fluorescence microscopy combined with computer image analysis (ImageJ software, NIH, USA). The aim of this study was to quantitatively characterize the movement of the IPCs and to evaluate the viscosity in the vacuoles using the obtained data. In the vacuoles of Saccharomyces cerevisiae yeast cells, vividly moving insoluble polyphosphate complexes (IPCs) <1 µm size, stainable by a fluorescent dye, 4 ,6-diamidino-2-phenylindole (DAPI), may appear under some growth conditions. ![]()
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