Abstract

Proteins from (hyper-)thermophiles are known to exhibit high intrinsic stabilities. Commonly, their thermodynamic characterization is impeded by irreversible side reactions of the thermal analysis or calorimetrical problems. Small single-domain proteins are suitable candidates to overcome these obstacles. Here, the thermodynamics of the thermal denaturation of the recombinant cold-shock protein (Csp) from the hyperthermophilic bacterium Thermotoga maritima (Tm) was studied by differential scanning calorimetry. The unfolding transition can be described over a broad pH range (3.5-8.5) by a reversible two-state process. Maximum stability (DeltaG (25 degrees C)=6.5 kcal/mol) was observed at pH 5-6 where Tm Csp unfolds with a melting temperature at 95 degrees C. The heat capacity difference between the native and the denatured states is 1.1(+/-0.1) kcal/(mol K). At pH 7, thermal denaturation occurs at 82 degrees C. The corresponding free energy profile has its maximum at 30 degrees C with DeltaGN-->U=4.8(+/-0.5) kcal/mol. At the optimal growth temperature of T. maritima (80 degrees C), Tm Csp in the absence of ligands is only marginally stable, with a free energy of stabilization not far beyond the thermal energy. With the known stabilizing effect of nucleic acids in mind, this suggests a highly dynamical interaction of Tm Csp with its target molecules. Study holds ProTherm entries: 5478, 5479, 5480, 5481, 5482, 5483, 5484, 5485, 5486, 5487, 5488, 5489, 5490, 5491, 5492, 5493, 5494, 5495, 5496, 5497, 5498, 5499 Extra Details: cold-shock protein; differential scanning calorimetry(DSC);,hyperthermophiles; stability; Thermotoga maritima

Submission Details

ID: nqSLd7xn

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:30 p.m.

Version: 1

Publication Details

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