DIFFERENTIAL SCANNING CALORIMETRY STUDY OF THE THERMODYNAMIC STABILITY OF SOME MUTANTS OF SSO7D FROM SULFOLOBUS-SOLFATARICUS

Citation
F. Catanzano et al., DIFFERENTIAL SCANNING CALORIMETRY STUDY OF THE THERMODYNAMIC STABILITY OF SOME MUTANTS OF SSO7D FROM SULFOLOBUS-SOLFATARICUS, Biochemistry, 37(29), 1998, pp. 10493-10498
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
Journal title
Biochemistry → ACNP
ISSN journal
0006-2960
Volume
37
Issue
29
Year of publication
1998
Pages
10493 - 10498
Database
ISI
SICI code
0006-2960(1998)37:29<10493:DSCSOT>2.0.ZU;2-6
Abstract
Sso7d from the thermoacidophilic archaebacterium Sulfolobus solfataric us is a small globular protein with a known three-dimensional structur e. Inspection of the structure reveals that Phe31 is a member of the a romatic cluster forming the protein hydrophobic cole, whereas Trp23 is located on the protein surface and its side chain exposed to the solv ent. The thermodynamic consequences of the substitution of these two r esidues in Sso7d have been investigated by comparing the temperature-i nduced denaturation of Sso7d with that of three mutants: F31A-Sso7d, F 31Y-Sso7d, and W23A-Sso7d. The denaturation processes proved to be rev ersible for all proteins, and represented well by the two-state N <-> D transition model in a wide range of pH. All three mutants are less t hermally stable than the parent protein; in particular, in the pH rang e of 5.0-7.0, the F31A substitution leads to a decrease of 24 degrees C in the denaturation temperature, the F31Y substitution to a decrease of 10 degrees C, and the W23A substitution to a decrease of 6 degrees C. A careful thermodynamic analysis of such experimental data is carr ied out.