Protein reversibility

Lau, S. Y. M., Taneja, A. K., and Hodges, R. S., Effects of high-performance liquid chromatographic solvents and hydrophobic matrices on the secondary and quaternary structure of a model protein. Reversed-phase and size exclusion high-performance liquid chromatography, /. Chromatogr., 317, 129, 1984. 

When a protein reversibly unfolds in solution, it enters a large and diverse ensemble of conformations known as the denatured state. Studies of this reaction over the past 40 years have suggested it is a single,... 

Bizzarri R, Serresi M, Cardarelli F, Abbruzzetti S, Campanini B, Viappiani C, Beltram F (2009) Single amino acid replacement makes Aequorea victoria fluorescent proteins reversibly photoswitchable. J Am Chem Soc 132 85-95... 

Although RP-HPLC has proven its analytical usefulness, its routine application to analysis of specific protein preparations should be undertaken only after extensive validation studies. HPLC in general can have a denaturing influence on many proteins (especially larger, complex proteins). Reverse-phase systems can be particularly harsh, as interaction with the highly hydrophobic stationary phase can induce irreversible protein denaturation. Denaturation would result in the generation of artifactual peaks on the chromatogram. 

Other molecular thermodynamic models for protein-reverse micelle complexes have also emerged. Bratko et al. [171] presented a model for phase transfer of proteins in RMs. The shell and core model was combined with the Poisson-Boltzmann approximation for the protein-RM complex and for the protein-free RM. The increase in entropy of counterions released from RMs on solubilization of a protein was the main contribution to the decrease in free energy of com-plexation. Good agreement was found with SANS results of Sheu et al. [151] for cytochrome C solubilization and the effect of electrolytes on it. However, this model assumes that filled and empty RMs are of the same size, independent of salt strength and pH, which is not true according to experimental evidence available since then. 

In the case of most enzymic transformations the reaction rate can be described as a hyperbolic function of the concentration of substrate the characteristic parameters of these hyperboles are the and the KM values, which can be determined easily by different linearized plots. Different factors such as temperature, pH, chemical modification of the functional groups in the side chains of the protein, reversible inhibitors, activators, allosteric effectors, influence the catalytic activity of the enzymes. 

Acetonitril is often recommended because of its separating power (cf. Fig. 5). Adding a small amount of trifluoroacetic acid (TFA) to both gradient components A and B, is state of the art in protein reversed-phase chromatography. It decreases retention time, improves resolution, and increases the recovery of the sample proteins. 

Optimization of protein Separation of cereal proteins Reversed-phase 114, 123, 127, 131-133... 

Synthesis of viral capsid protein, envelope protein, reverse transcriptase. Assembly of new virus and release by budding... 

Fig. 10. The structure of mouse DNA containing the integrated mouse mammary tumour provirus. The integrated viral DNA can be present in many copies. The provirus contains two long terminal repeat sequences, LTR, only one of which (left) is shown in detail here. Each LTR contains sequences termed U3, R and U5 (for details, see Ref. 67). Interspersed between the LTRs are the genes named gag, pol and env, encoding viral coat proteins, reverse transcriptase and envelope proteins, respectively. The glucocorticoid-binding sequence is represented by the black box, and the transcriptional initiation area is indicated by the hatched box.

Proteins, Reversible Denaturation of. Methods of Study and Interpretation of Data... 

Here again, not all chromatographic setups are usable for any proteomics question. The use of protein reverse phase chromatography, which has been advocated for plasma proteomics (Moritz et al. 2005), precludes in turn the use of any detergent of any type. This prevents the use of this chromatographic setup in most subcellular proteomics experiments, where detergents must be used to solubilize the membrane limiting the subcellular compartments. 

NOE pumping Ligand or protein (reverse) None None Bound conformation lO-MO- M X y X r... 

Protein synthesis in the body is constrained to 20 amino acids (including the imino acid proline), but modifications made after translation greatly extend the range of side chains found in mature proteins. Reversible modifications provide opportunities for regulation of protein function. 

Peptides and proteins Reversed phase, size exclusion and ion exchange Various Various 111... 

By the same token, the chemical composition of the substrate may play a major role in protein adsorption, since highly hydrophilic (hydrogel) surfaces tend to adsorb plasma proteins reversibly with little damage, whereas hydrophobic surfaces cause strong and partially irreversible adsorption leading to extensive damage of adsorbed proteins. 

The in situ desorption experiments on polymer or mica surfaces are performed using the apparatus shown in Figure 5b. The protein solution is pumped out of the cell and simultaneously replaced by water or a buffer solution. Multiple replacement operations lead to a negligible protein concentration in the cell. The Ab value being zero, the measured radioactivity after allowing for the absorption of radiation by a solid sample is directly converted into the surface concentration of the irreversibly adsorbed protein. The loosely bound protein (reversibly adsorbed protein) as a fraction of the total adsorbed layer, is thus obtained by subtraction of the irreversible adsorption from the total adsorption value. 

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