Chaotropic agents, protein

Low inorganic ions level (stability of macromolecules, chaotropic agents, protein synthesis, etc.). 

Folded proteins can be caused to spontaneously unfold upon being exposed to chaotropic agents, such as urea or guanidine hydrochloride (Gdn), or to elevated temperature (thermal denaturation). As solution conditions are changed by addition of denaturant, the mole fraction of denatured protein increases from a minimum of zero to a maximum of 1.0 in a characteristic unfolding isotherm (Fig. 7a). From a plot such as Figure 7a one can determine the concentration of denaturant, or the temperature in the case of thermal denaturation, required to achieve half maximal unfolding, ie, where... 

Urea, ranging from 5 to 9 M, is the most common choice of chaotropic agent, and disruption of hydrogen and hydrophobic bonding between proteins is the main mode of action. When used in conjunction with thiourea (from 0 to 2 M), the two can aid solubilization of poorly soluble samples. The use of urea or urea-thiourea mixtures in SD buffers has no effect on the charge of the proteins within the sample. This is ideal for use in separating proteins according to their p in the first... 

Precautions should also be taken with the aqueous solvents used to prepare standard working solutions in order to avoid adsorption problems, especially at low concentrations. To minimize adsorption during standard curve and validation sample (VS)/QC preparations, aliquots of the high-concentration stock solutions should be spiked promptly into the control blank plasma to prepare the standards and VS/QC. Once the compounds are in an environment of protein solutions, the adsorption problem is negligible. If there is a problem, however, adding or pre-rinsing with a solution of protein or a chaotropic agent (e. g., Tween, Triton X-100 or CHAPS) may help to alleviate the problem. 

Although guanidine hydrochloride is a potent chaotropic agent, its use for RNA isolation has not been as popular as that of guanidine thiocyanate. The reasons may be that it needs to be used at a much higher concentration to be an effective protein denaturant. The method described here is a modification of methods described in Refs. 15 and 16. 

In many cases the target protein is bound to membranes or particles or is aggregated as a consequence of its hydrophobic characteristics. In these cases, detergents and chaotropic agents can be used to weaken these interactions during cell disruption and extraction steps. The detergent performance is highly dependent on pH and temperature. 

One global property suitable for evaluation of evolutionary intermediates is protein stability. The unique biological and physical properties of an enzyme are highly dependent on the integrity of its native conformation. The structural stability of a protein can be measured by its resistance to heat, acid, and various chaotropic agents. Measurements of the thermostability of lysozymes provide an easy and an accurate way to assess the protein stability. 

A disk-stack centrifuge is used for cell harvesting. A high-pressure ho-mogenizer is utilized to break the cells and release the inclusion bodies. These inclusion bodies are recovered in another disk-stack centrifuge. The inclusion bodies are then solubilized in a well-mixed reactor with urea. This chaotropic agent dissolves the denatured protein. A filter is used to remove the fine particles such as biomass, debris, and inclusion bodies. 

Y. Hatefi and W. G. Hanstein, Solubilization of particulate proteins and nonelectrolytes by chaotropic agents, Proc. Natl. Acad. Sci. USA 62 (1969), 1129. 

Chaotropic agents guanidine hydrochloride use for study of protein denaturation GTIC is considered to be more effective than GuCl GTIC used for nucleic acid extraction. 

Thiocarbamide 76.12 Chaotropic agent useful for membrane proteins will react with haloacetyl derivatives such as iodoacetamide protease inhibitor. 

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