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Thermophiles proteins

The high thermostability in the thermophilic counterpart was due to amino acid residues located in three distal regions of the protein as shown in Fig. 2. " The introduction of five selected mutations in those regions of Pac-55 caused the protein to attain a similar thermostability to that of the thermophilic protein probably due to a tighter side chain packing and increased total accessible surface area. " ... [Pg.132]

Some good hints to help answer this question have been obtained by studying thermophilic proteins which are in turn obtained from thermophilic organisms. The optimum growth temperature for thermophilic organisms is between 40° and 65°C (moderate thermophiles) and 70° and 105°C (extreme thermophiles). Their respective enzymes have catalytically indistinguishable reactivity and catalytic sites from those isolated from mesophilic organisms. [Pg.507]

Directed evolution as a tool to probe the basis of protein structure, stability, and function is in its infancy, and many fruitful avenues of research remain to be explored. Studies so far have focused on proteins that unfold irreversibly, making detailed thermodynamic analysis impossible. The application of these methods to reversibly folding proteins could provide a wealth of information on the thermodynamic basis of high temperature stability. A small number of studies on natural thermophilic proteins have identified various thermodynamic strategies for stabilization. Laboratory evolution makes it possible to ask, for example, whether proteins have adopted these different strategies by chance, or whether certain protein architectures favor specific thermodynamic mechanisms. It will also be possible to determine how other selective pressures, such as the requirement for efficient low temperature activity, influence stabilization mechanisms. The combination of directed evolu-... [Pg.220]

Gromiha MM, Oobatake M, Sarai A. Important amino acid properties for enhanced thermostability from mesophilic to thermophilic proteins. Biophys. Chem. 1999 82 51-67. [Pg.2010]

Szilagyi A, Zavodszky P. Structural differences between meso- 25. philic, moderately thermophilic and extremely thermophilic protein subunits results of a comprehensive snrvey. Stmcture 2000 8 493-504. 26. [Pg.2011]

Analysis of the sequence data obtained from various GAPDH and PGK molecules shows that adaptation to the higher temperature is accompanied by an increase of average hydrophobicity and a decrease of chain flexibility. Similar trends have also been deduced from comparisons of bacterial proteins adapted to different temperatures [17,18]. Although the difference in these parameters catmot be quantitatively correlated with changes in thermophilicity, nevertheless these trends are indicative of the importance of hydrophobic interactions and chain rigidity for the structure of thermophilic proteins. [Pg.213]

N. Ferguson, R. Day, C. M. Johnson, M. D. Allen, V. Dagget, A. Fersht (2005) Simulation and experiment at high temperatures Ultrafast folding of a thermophilic protein by nucleation-condensation. J. Mol. Biol. 347, pp. 855-870... [Pg.431]

Cowan DA. Thermophilic Proteins Stability and Function in Aqueous and Organic Solvents. Comp Biochem Physiol 1997 118 429-438. [Pg.391]

La, D Silver, M Edgar, R. C and Livesay, D. R. (2003) Using motif-based methods in multiple genome analyses a case study comparing orthologous mesophilic and thermophilic proteins. Biochemistry 42, 8988-8998. [Pg.290]

Aside from the cases mentioned above, Thermus metabolic engineering efforts have been limited. Although the native products (e.g., carotenoids) in Thermus species have not been an area of great interest, Thermus species can serve as effective hosts for expression of thermophilic proteins. Furthermore, T. thermophilus has the potential to be engineered with multiple genes [253] for in... [Pg.547]

The 7-kDa Sulfolobus chromatin proteins are especially amenable to studies of both protein stability and DNA-binding. They unfold reversibly over a wide range of temperature, pH, and salt concentration, thus permitting an extensive characterization of thermophile protein stability.In addition, they bind to DNA with a relatively small site size, which facilitates a detailed study of the energetics of DNA-binding by site-directed mutagenesis. [Pg.130]

HX due to local fluctuations is unavoidably in the EX2 limit. Exchange due to unfolding reactions may press these limits, especially when measured under extreme conditions, e.g., with thermophilic proteins. Tests for EX2 behavior include the classical experiment for simple pH dependence, " the difficult and relatively noisy nuclear overhauser effect (NOE) correlation experiment, and most easily the comparison of the rates measured for several NHs in a cooperative unfolding with their expected chemical rates. ... [Pg.346]

Oligomer Stability. Many thermophile proteins are oligomers that require some special considerations—specifically the need to specify concentration when discussing stability. Total protein concentration does not enter into the expressions for the stability of monomeric proteins. This is not the case for oligomers because... [Pg.405]

Effect of pH on Protein Stability. Electrostatic interactions are thought to be important in conferring increased stability in thermophile proteins. The effect of pH on stability can be used to quantitatively probe the location and importance of these interactions, since ionic interactions must perturb the pK values of the groups involved. ... [Pg.416]

Fig. 1. Hypothetical temperature profiles of the free energy of (a) mesophilic and (b-d) thermophilic proteins. AC is defined as the difference in the free energies between the native and denatured states. Tm and are the melting temperatures of the mesophilic and thermophilic variants, respectively. The minimum of the AC parabola for a given protein (i.e., maximum stability) is observed at a temperature that is much below the optimal temperature (Topt and T p,) of the respective mesophilic or thermophilic organism. Fig. 1. Hypothetical temperature profiles of the free energy of (a) mesophilic and (b-d) thermophilic proteins. AC is defined as the difference in the free energies between the native and denatured states. Tm and are the melting temperatures of the mesophilic and thermophilic variants, respectively. The minimum of the AC parabola for a given protein (i.e., maximum stability) is observed at a temperature that is much below the optimal temperature (Topt and T p,) of the respective mesophilic or thermophilic organism.
But sometimes it isn t. In contrast to these data, a number of other thermophile/ mesophile structure comparisons have found no significant increase in the number of hydrogen bonds in the thermophilic protein. One example is the threefold comparison of Escherichia coli, Salmonella typhimurium, and Thermus ther-mophilus 3-isopropylmalate dehydrogenase structures where the number of nonsalt-bridge hydrogen bonds didn t change much. The authors of that study make... [Pg.472]


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See also in sourсe #XX -- [ Pg.209 , Pg.210 , Pg.211 , Pg.212 , Pg.213 , Pg.214 , Pg.215 , Pg.216 , Pg.217 ]




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