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DSC studies of the conformational stability of barstar wild‐type
Author(s) -
Schöppe Arnulf,
Hinz HansJürgen,
Agashe Vishwas R.,
Ramachandran S.,
Udgaonkar Jayant B.
Publication year - 1997
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560061014
Subject(s) - isothermal microcalorimetry , enthalpy , chemistry , mutant , denaturation (fissile materials) , crystallography , wild type , atmospheric temperature range , thermodynamics , biochemistry , nuclear chemistry , physics , gene
The temperature induced unfolding of barstar wild‐type of bacillus amyloliquefaciens (90 residues) has been characterized by differential scanning microcalorimetry. The process has been found to be reversible in the pH range from 6.4 to 8.3 in the absence of oxygen. It has been clearly shown by a ratio of δ H vH /δ H cal near 1 that denaturation follows a two‐state mechanism. For comparison, the C82A mutant was also studied. This mutant exhibits similar reversibility, but has a slightly lower transition temperature. The transition enthalpy of barstar wt (303 kJ mol −1 ) exceeds that of the C82A mutant (276 kJ mol −1 ) by approximately 10%. The heat capacity changes show a similar difference, δ C p being 5.3 + 1 kJ mol −1 K −1 for the wild‐type and 3.6 δ 1 kJ mol −1 K −1 for the C82A mutant. The extrapolated stability parameters at 25 °C are δ G ° = 23.5 + 2 kJ mol −1 for barstar wt and δ G 0 = 25.5 + 2 kJ mol −1 for the C82A mutant.