Presence Of Protein In Solution Research Articles

NMR Relaxation of Nuclei of Buffer as a Probe for Monitoring Protein Solutions Including Aggregation Processes

Characterization of protein solutions is of great importance for biophysical research, pharmaceutical industry, and medicine. Particularly, the monitoring of the protein aggregation is crucial at all stages of biotechnological production and in the diagnosis of dangerous diseases. The present work is focused on a study of prospects and possibilities of NMR relaxation of solvent nuclei for monitoring the state of proteins in solutions. The spin–lattice and spin–spin relaxation rates (R1 and R2) of solvent nuclei were measured in the solutions of a small globular protein, RRM2 domain of TDP-43 protein. The solvent was either H2O- or D2O-based buffer with pH 6.5 and contained 20 mM sodium phosphate and 150 mM NaCl. The relaxation rates of the solvent 1H, 2H, 23Na, and 35Cl nuclei in solutions of soluble and aggregated RRM2 domain of TDP-43 protein were studied. The aggregation was induced by mild oxidative stress, using treatment by hydrogen peroxide. It was found that aggregation of protein could be detected using NMR relaxation of 1H nuclei. The observed CPMG dispersion for R2 rates confirms the millisecond timescale for the hydrogen exchange between water and protein sites. The correlation times and binding constants for sodium and chlorine ions were estimated using concentration dependences for relaxation rates (23Na, 35Cl). The relaxation rates of solvent nuclei are sensitive to the presence of protein in solution even at low protein concentrations, and the relaxation rates of different nuclei reflect various aspects of the state of the protein.

Influence of Proteins and Cells on Corrosion of Mg

Mg based materials have been in the focus of increasing interest for temporary biomedical implants, where the device is only required for a certain time of healing. In spite of the large amount of work carried out in the field, many critical issues still remain, such as limited understanding of the interactions between the corroding Mg (alloy) surface and the biological environment. Results concerning the effects of biomolecules, proteins (and/or) cells on Mg corrosion are scarce and somewhat controversial. For instance, both acceleration or inhibition of Mg corrosion has been reported by proteins in the electrolyte. As the different observations are related to different experimental approaches, it is not straightforward to elucidate the reasons for the seeming discrepancies or the underlying mechanisms. The presentation will discuss some recent findings on interactions between Mg, proteins (mainly bovine serum albumin), and cells. Protein effects on corrosion were studied by electrochemical techniques on commercially-pure Mg and the Mg alloy AZ91. Surface analysis by XPS and ToF-SIMS indicate that proteins indeed adsorb on Mg surfaces and can inhibit corrosion but the effects are time- and material-dependent. In addition, the presence of proteins in solution change the composition of corrosion layers on the surface. Impedance spectroscopy investigations combined with in vitro cell culturing on Mg demonstrate a significant decrease of dissolution rate after certain time of cell growth.

Hypoosmotic swelling patterns in human spermatozoa: Effects of colloid osmotic pressure conditions

Objective: Addition of proteins to hypoosmotic media delays the swelling response as compared to hypoosmotic solutions without protein supplementation. The hypoosmotically-reactive spermatozoa are able to maintain motility, and even progressive motility without associated tail swelling, in the presence of proteins in solution. The aim of this study was to assess the sperm response at the onset of swelling, and also during the development of the tail swelling patterns until reaching their optimal response under hypoosmotic conditions regulated by the presence of proteins.

Floc structure and the role of cations

Cations have been found to influence the settling and dewatering characteristics of biological sludges. This research was directed at investigating the role of iron in floc stability of sensitivity to shear and in the response to anaerobic and aerobic digestion. Our data shows that iron may contribute to floc strength and it appears that the deterioration in sludge dewatering during anaerobic digestion is associated with the reduction and solubilization of iron. Further, it is the presence of proteins in solution that contributes to poor dewatering and to the demand for conditioning chemicals. The addition of iron for improving dewatering shows that iron may selectively coagulate solution proteins.

Indirect method for quantitative determination of bovine serum albumin and transferin by anodic stripping voltammetry with a rotating glassy carbon electrode

The present study was carried out in order to investigate whether the interaction of multifunctional transport proteins, bovine serum albumin (BSA) and transferin (TF), with some metal (Me) ions, such as Hg(II) and Cu(II), in buffered solution (pH 8.0), may serve as a base for indirect quantitative determination of both proteins. For this purpose anodic stripping voltammetry with a rotating glassy carbon electrode was applied. A sufficient sensitivity on the presence of protein in solution containing Me-ions was obtained only by using a mercury dissolution signal (peak) observed at 0.1 V vs. SCE. Quantities of BSA less than 5×10 −7 M were determined with a S.D.±5% ( n=10) for a concentration of 3×10 −7 M, and for TF the concentration less than 1.5×10 −7 M could be determined with S.D.±4% ( n=10) for a concentration of 1×10 −7 M.

Size Exclusion Removal of Model Mammalian Viruses Using a Unique Membrane System, Part I: Membrane Qualification

Abstract. We have previously described a new class of composite membrane that has the capability to efficiently remove particles, including viruses, from protein solution. The qualification of this membrane requires that it reproducibly and predictably remove model mammalian viruses. Using the Viresolve/70™ membrane, the mammalian viruses polio, Simian virus-40, Sindbis, reovirus type 3 and Rauscher murine leukemia virus are shown to be reproducibly removed via a sieving mechanism. Mammalian virus retention increases constantly with virus diameter independent of virus class or type, increasing from 3·5 logs with polio virus to greater than 6·8 logs with murine leukemia virus. Consistent with a sieving mechanism, mammalian virus retention with the Viresolve/70™ membrane is independent of virus concentration. These results are shown both in the presence and absence of protein in solution. The presence of protein in solution is shown to increase the virus retention coefficient of each virus above that measured in phosphate buffered saline. The model virus retention is shown to be well predicted by hard particle retention reported previously for this membrane. In addition, the hard particle retention is shown to predict the worse case performance expected of the membrane in the presence of protein.