Thermodynamic stability of two variants of xylanase (Xys1) from Streptomyces halstedii JM8
Related Experiment Video
Updated: Oct 29, 2026

How to Stabilize Protein: Stability Screens for Thermal Shift Assays and Nano Differential Scanning Fluorimetry in the Virus-X Project
Published on: February 11, 2019
A Ruiz-Arribas1, G G Zhadan, V P Kutyshenko
1Instituto de Microbiología Bioquímica/Departamento de Microbiología Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Spain.
Abstract:
In a continuation of our earlier study [Ruiz-Arribas, A., Santamaría, R.I., Zhadan, G. G., Villar, E. & Shnyrov, V. L. (1994) Differential scanning calorimetric study of the thermal stability of xylanase from Streptomyces halstedii JM8, Biochemistry 33, 13787-13791], we used high-sensitivity differential scanning microcalorimetry, intrinsic tryptophan fluorescence and far-ultraviolet circular dichroism to study the effect of regional sequence differences on the thermodynamic stability of xylanase (Xys1) from Streptomyces halstedii JM8 (1,4-beta-D-xylanohydrolase, EC 3.2.1.8). Thermal transitions were measured for original xylanase (Xys1S) and two variants. Thermal denaturation of all the xylanases studied revealed two structural domains, each of which, despite its partial irreversibility, follows a two-state thermal unfolding process under our experimental conditions. Both variants were found to exhibit slightly decreased stability, possessing the same activity as the original. The unfolding parameters for each domain of both variants, unlike the situation with wild-type xylanase (see our previous report), fit some correlations obtained for the most compact globular proteins. The values of enthalpy and entropy of unfolding/residue at 383 K were found to be inversely proportional to residual, well-regulated structures in unfolded states.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Stability of Conjugated Dienes
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
Types of Enols and Enolates
Bioreactor Controls-III
Enzyme Kinetics
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control

