Temperature proteins

Litvinenko KL, Webber NM, Meech SR (2003) Internal conversion in the chromophore of the green fluorescent protein Temperature dependence and isoviscosity analysis. J Phys Chem A 107 2616-2623... 

Temperature-sensitive mutations usually arise from a single mutation s effect on the stability of the protein. Temperature-sensitive mutations make the protein just unstable enough to unfold when the normal temperature is raised a few degrees. At normal temperatures (usually 37°C), the protein folds and is stable and active. However, at a slightly higher temperature (usually 40 to 50°C) the protein denatures (melts) and becomes inactive. The reason proteins unfold over such a narrow temperature range is that the folding process is very cooperative—each interaction depends on other interactions that depend on other interactions. 

Dicko, C., Knight, D., Kenney, J. M., and Vollrath, F. (2004b). Secondary structures and conformational changes in flagelliform, cylindrical, major, and minor ampullate silk proteins. Temperature and concentration effects. Biomacromolecules 5, 2105-2115. 

In copper and silver complexes, optimum ENDOR enhancements for all types of nuclei are usually achieved for tempeatures between 10 to 30 K. For Cu-ENDOR in copper containing proteins, temperatures 4K are sometimes required (see below). 

Andrade SM, Costa SMB (2002) Aggregation kinetics of meso-tetrakis(4-sulfonatophenyl) porphine in the presence of proteins temperature and ionic strength effects. J Fluoresc 12 77-82... 

E. A. Permyakov and E. A. Burstein, Relaxation processes in frozen aqueous solution of proteins temperature dependence of fluorescence parameters, Stud. Biophys. 51, 91-103 (1975). 

In order to be exploitable for extraction and purification of proteins/enzymes, RMs should exhibit two characteristic features. First, they should be capable of solubilizing proteins selectively. This protein uptake is referred to as forward extraction. Second, they should be able to release these proteins into aqueous phase so that a quantitative recovery of the purified protein can be obtained, which is referred to as back extraction. A schematic representation of protein solubilization in RMs from aqueous phase is shown in Fig. 2. In a number of recent publications, extraction and purification of proteins (both forward and back extraction) has been demonstrated using various reverse micellar systems [44,46-48]. In Table 2, exclusively various enzymes/proteins that are extracted using RMs as well as the stability and conformational studies of various enzymes in RMs are summarized. The studies revealed that the extraction process is generally controlled by various factors such as concentration and type of surfactant, pH and ionic strength of the aqueous phase, concentration and type of CO-surfactants, salts, charge of the protein, temperature, water content, size and shape of reverse micelles, etc. By manipulating these parameters selective sepa-... 

Leikin, S., Rau, D. C., and Parsegian, V. A. (1994). Direct measurement of forces between self-assembled proteins. Temperature-dependent exponential forces between collagen triple-helices. Proc. Natl. Acad. Sci. 91, 276-280. 

As yet, for the majority of other GFP proteins temperature stability has not been investigated. 

Several publications have reported electrofocusing carried out at room temperature, but it is better to keep the temperature as low as possible because electrofocusing sometimes takes several hours and lower temperatures lessen the risks of denaturation of the proteins. Temperatures close to 0°C or under it should be avoided. This is because the viscosity of the sucrose-Ampholine solution has a temperature coefficient which is nearly constant down to around 0°C. The same is the case with the conductivity. Just under 1°C the temperature coefficient suddenly rises steeply. This means that at 0°C a slight discrepancy between the tern-... 

Table 9.2. Cl relaxation of CIO4 in the presence of com-plexes between Hg or Zn and human serum albumin. All solutions contained 1.2 M NaCl04 and 2.2 10 M protein. Temperature 28°C and pH 7.4. (According to measurements by Reimars-son [236])...

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