Abstract

Lambda repressor (l6-85) is a soluble fragment of lambda repressor containing residues 6 to 85 which maintains a native-like fold consisting largely of alpha helices. Differential scanning calorimetry (DSC) of the WT (l6-85) and the double mutant G46A/G48A reveal that the effect of the mutations is to stabilize the protein by ~ 1.5 kcal/mol at 25 C (I.e., 2.9 kcal/mol for the WT and 4.4 kcal/mol for G46/48A). The increase in stability upon mutation suggests that the primary effect of the mutation on stability is the decrease in conformational entropy ( Sconf) of the unfolded state when Gly is replaced by Ala. However, as the calculated effect of changing Gly to Ala at two positions in a helix is ~ 2.4 kcal/mol, the ~0.9 kcal/mol difference between the experimental and calculated values suggests that additional effects arise from the mutations which decrease the stability of the native state of the double mutant.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR004328-10
Application #
6122019
Study Section
Project Start
1997-08-05
Project End
1998-08-04
Budget Start
Budget End
Support Year
10
Fiscal Year
1997
Total Cost
Indirect Cost

  Institution

Name
Johns Hopkins University
Department
Type
DUNS #
045911138
City
Baltimore
State
MD
Country
United States
Zip Code
21218

  Publications

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Griko, Y V; Remeta, D P (1999) Energetics of solvent and ligand-induced conformational changes in alpha-lactalbumin. Protein Sci 8:554-61
Chu, V; Freitag, S; Le Trong, I et al. (1998) Thermodynamic and structural consequences of flexible loop deletion by circular permutation in the streptavidin-biotin system. Protein Sci 7:848-59
Luque, I; Freire, E (1998) Structure-based prediction of binding affinities and molecular design of peptide ligands. Methods Enzymol 295:100-27
Luque, I; Gomez, J; Semo, N et al. (1998) Structure-based thermodynamic design of peptide ligands: application to peptide inhibitors of the aspartic protease endothiapepsin. Proteins 30:74-85
Gomez, J; Semo, N; Freire, E (1998) Structural thermodynamic study of the binding of renin inhibitors to endothiapepsin. Adv Exp Med Biol 436:325-8
Koder, R L; Miller, A F (1998) Overexpression, isotopic labeling, and spectral characterization of Enterobacter cloacae nitroreductase. Protein Expr Purif 13:53-60
Freire, E (1998) Statistical thermodynamic linkage between conformational and binding equilibria. Adv Protein Chem 51:255-79

Showing the most recent 10 out of 86 publications