What factors contribute to protein stability at very extreme temperatures? What gain comes from entropy and enthalpy? And how to account for the delicate effect of temperature on molecular interactions like the hydrophobic and ionic ones? All this is tackled in a very intriguing work by Y. Matsura et al. "Thermodynamics of protein denaturation at temperature over 100°C: CutA1 mutant proteins substituted with hydrophobic and charged residues" recently published in Scientific Reports [see here]. By designing sequential mutations the authors were able to construct hyper-stable versions of the CutA1 protein and to extract the main thermodynamic parameters characterising their thermal stability. It is a very important work challenging both technical biochemical problems, like the aggregation of proteins generally occurring above 80°C, and the basic thermodynamics controlling protein stability over 100°C where for instance hydrophobic interactions cease to be entropically driven and ion-pairing can benefit from water dielectric constant decrease. Tuesday, November 17, 2015
Over 100°C
What factors contribute to protein stability at very extreme temperatures? What gain comes from entropy and enthalpy? And how to account for the delicate effect of temperature on molecular interactions like the hydrophobic and ionic ones? All this is tackled in a very intriguing work by Y. Matsura et al. "Thermodynamics of protein denaturation at temperature over 100°C: CutA1 mutant proteins substituted with hydrophobic and charged residues" recently published in Scientific Reports [see here]. By designing sequential mutations the authors were able to construct hyper-stable versions of the CutA1 protein and to extract the main thermodynamic parameters characterising their thermal stability. It is a very important work challenging both technical biochemical problems, like the aggregation of proteins generally occurring above 80°C, and the basic thermodynamics controlling protein stability over 100°C where for instance hydrophobic interactions cease to be entropically driven and ion-pairing can benefit from water dielectric constant decrease. 
Sunday, November 1, 2015
Water helps life in extreme environments?
A few months ago we published an explorative work focusing on the possible contribution of water molecules buried in the interior of proteins to their different thermal stabilities [see here for the paper]. The study-case was a pair of homologous GTPase domains from a mesophilic and a hyperthermophilic organism, respectively. Now, we extended our approach by considering a large set of homologous pairs. Let's list the main findings. Firstly, for some homologues internal water gives a meaningful contribution to the stability gap in favour of the thermophilic variant. This was probed at ambient condition. Secondly, when considering the behaviour at high temperature, we found that thermophilic proteins are more keen to maintain their internal cavities wet, and therefore benefiting by this wetting. We propose that internal hydration can be viewed as an alternative tuneable variable for the engineering of proteins with enhanced stability. Enjoy the manuscript here.
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