Solvent denaturation

Herskovits TT, Jaullet H. On the structural stability and solvent denaturation of proteins. J. Biol. Chem. 1970 245 2588-2598. 

Fig. 13 Solvent denaturation titrations of 34 (filled diamond) and 35 (filled square) showing the full range of folded and unfolded character...

Fig. 23 Solvent denaturation curves of 45 measured by a the UV absorbance ratio A303M287 and b the circular dichroism (g bs at 316 nm) showing the need for higher vol% acetonitrile to bring about twist sense bias than that needed for folding...

In an effort to impart a stronger twist sense bias on the mPE helix, a chiral binaphthol derivative was placed directly into the mPE backbone [64]. The chiral binaphthol unit was placed both at the center (47) and terminus (48) of the oligomer in order to determine how the position of the chiral unit would affect the twist sense bias and folded state stability. Solvent denaturation studies (UV... 

Incorporation of an imine unit into a mPE began with a Monte Carlo search of dodecamer (58e), which indicated that the oligomer adopted a six-turn helical structure [86]. To verify these results solvent denaturation studies were performed on 58e which showed a helix coil transition with a AG(CH3CN) very similar to that of the native oligomers (3.0 0.2 for 58e vs 3.2 0.1 for 15). The small difference in the AG(CH3CN) indicates that the imine bond has a negligible effect on the stability of the folded state of the oligomer. With this... 

Because mD N is proportional to the number of groups in the protein, large proteins are more sensitive to solvent denaturation than small ones. It is a common mistake to attribute resistance to solvent denaturation of small proteins to high stability in fact, it is an inherent characteristic of a small change in surface area on denaturation. Also, proteins that are elongated have higher solvent exposure in the native state and correspondingly lower values of mD N. 

Immobilization has other advantages it can slow enzyme deactivation by inhibiting protease attack and minimizing shear, interfacial, temperature, or solvent denaturation. As for the scarcity of some potentially very useful enzymes, it may be only a temporary problem. The development of cloning techniques, and probably the very increase in demand will result in lower prices. One spectacular instance is sialyl aldolase (see Table I). Industrial production of this enzyme by the gene-cloned strain of Escherichia coli has been reported.1,2 Sialylaldolase is now available from Toyobo at a moderate price. 

Schellman, J.A. (2002) Fifty years of solvent denaturation, Biophys.Chem. 96, 91-101 ... 

The third method is useful only if the desired protein is quite resistant to organic solvent denaturation. Such resistance permits organic solvent fractionation to be performed in much the same manner as described for ammonium sulfate fractionation the same considerations apply. As shown in Table 10-2, nearly all of the castor bean catalase in this preparation remains in solution at an ethanol concentration of 40% (v/v). Most proteins have already precipitated under these conditions and may be removed by centrifugation. Increasing the ethanol concentration to 60% precipitates catalase, permitting its recovery by centrifugation. 

Organic solvents denature proteins by disrupting hydrophobic interactions. 

Problems Ammonium sulfate and PEG do not precipitate the protein or do so incompletely from diluted solutions, and the precipitation with ammonium sulfate results in large amounts of often undesirable ions. The organic solvents denature some proteins even at low temperatures. 

A thermodynamic analysis of solvent denaturation is applied here to the abrupt conformational transition occurlng in hyaluronate solutions buffered in phosphate when the pH is changed... 

Schelhnan, J. A. 1987. Selective binding and solvent denaturation. Biopolymers. 26, 549. 

Common alcohols are used as solvents, denaturing agents, chemical feedstocks, and in antifreeze preparations. Ethanol is the intoxicating ingredient in alcoholic beverages. Propane-1,2,3,-triol (glycerol) is used to make polymers, cosmetic emollients, and sweeteners. 

Investigation of the equilibrium between native and unfolded conformations formed on solvent denaturation, temperature, and pressure have now been performed on a wide range of proteins. For example, James and Sawan have studied the effect of increasing guanidinium chloride concentration on the mobility of individual histidine residues in ribonuclease (pancreatic) C n.m.r. spectroscopy using spin-lattice relaxation in an off-resonance rotating frame. They found that L-histidines-12, -105, and -119 increase in mobility up to a denaturant concentra-... 

Liu S, Gibb BC. Solvent denaturation of supramolecular capsules assembled via the hydro-phobic effect. Chem Coimntm 2011 47 3574-6. 

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