Protein stability, enhancing

Properly folded native proteins tend to aggregate less than when unfolded. Solution additives that are known to stabilize the native proteins in solution may inhibit aggregation and enhance solubility. A diverse range of chemical additives are known to stabilize proteins in solution. These include salts, polyols, amino acids, and various polymers. Timasheff and colleagues have provided an extensive examination of the effects of solvent additives on protein stability [105]. The unifying mechanism for protein stabilization by these cosolvents is related to their preferential exclusion from the protein surface. With the cosolvent preferentially excluded, the protein surface is... 

AET activities are based upon its expertise in the field of protein biotechnology and are oriented to the area of protein stabilization technology and to the development and production of stabilized biosensors. The AET biosensor activities are enhanced by support and synergy with its sister companies Gwent Electronic Materials Ltd. and Gwent Sensors Ltd. 

Eggers, D.K. and Valentine, J.S. (2001) Molecular confinement influences protein structure and enhances thermal protein stability. Protein Science, 10, 250-261. 

Mesoporous silicas have characteristics of high specific surface areas and pores with defined dimensions and uniform distribution. These features make mesoporous systems ideal candidates as host materials to guest bio-molecules. Protein stability may be enhanced due to reduced autolysis in the case of protease enzymes, and more generally reduced protein aggregation, as a result of the separation of the molecules adsorbed on the surface. 

Highly fluorinated amino acids, such as hexafluoroleucine and hexafluorovaline, enhance the stability of several helical proteins. This enhancement has been attributed to the higher hydrophobicity of the fluorocarbon side chain compared to that of the natural hydrocarbon side chain. 

Sojiknl, P., Bnehner, N and Mason, H.S. (2003). A plant signal peptide-hepatitis B snrface antigen fusion protein with enhanced stability and immunogenicity expressed in plant cells. Proc. Natl. Acad. Sci. U.S.A. 100(5) 2209-2214. 

Industrialization and need for increase in agricultural activity, 1-2 Inosine monophosphate, taste enhancer, 17,19 Interdroplet forces, effect on centrifugal stability for protein-stabilized oil-in-water emulsions,... 

TABLE 5.8. Examples of excipients used to enhance protein stability in solution and lyophilized formulations... 

The strength of fibrous proteins is enhanced by covalent cross-links between polypeptide chains within the multihelical ropes and between adjacent chains in a supramolecular assembly. In a-keratins, the cross-links stabilizing quaternary structure are disulfide bonds (Box 4-2). In the hardest and toughest a-keratins, such as those of rhinoceros horn, up to 18% of the residues are cysteines involved in disulfide bonds. 

Nguyen T, Sherratt PJ, Huang HC, Yang CS, Pickett CB. 2003. Increased protein stability as a mechanism that enhances Nrf2-mediated transcriptional activation of the antioxidant response element. Degradation of Nrf2 by the 26 S proteasome. J Biol Chem 278 4536 4541. 

Towards Larger Proteins by Nonuniform Labeling and Stability Enhancement... 

Figure 5,20 Portion of a 3D X-filtered NOESY spectrum of uniformly 13C/15N-labeled, stability-enhanced kinaseX in complex with kinaseX inhibitor 2. The protein and inhibitor concentrations used were 300 pM. The F3 (inhibitor1H) plane is at 7.83 ppm. Peaks with protein resonance assignments are labeled. (Note Val-A and Val-B refer to the y-i and y methyl, respectively of the same valine residue.) The spectrum was recorded at 35 °C, 600 MHz 1H frequency using a NOESY mixing time of 100 ms on a Varian Inova spectrometer equipped with a Cold Probe. The spectrum is aliased in the 13C (F2) dimension.

Bommarius, A. S., Broering, J. M., Chaparro-Riggers, J. F. and Polizzi, K. M. (2006). High-throughput screening for enhanced protein stability. Curr. Opin. Biotechnol. 17, 606-610. 

Since there are strict stereochemical requirements for the relative positions and orientations of the two participating cysteine residues,11 addition of new disulfides to existing proteins by site-directed mutagenesis has not always produced the desired increase in stability. Introduction of disulfide bonds has been attempted for phage T4 lysozyme,4-71 phage A repressor,81 dihydrofolate reductase,91 and subtilisins.10-131 Among them the most extensive study has been performed on T4 lysozyme, and enhancement of protein stability has been successful. 

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