The thermal denaturations of five revertant λ repressors containing single amino acid substitutions in their N‐terminal domains have been studied by differential scanning calorimetry. Two substitutions slightly decrease stability, and the remaining three render the protein more stable than wild type. The Gly48 → Asn and Gly48 → Ser proteins are 4°C more stable than wild type. These two substitutions replace an α helical residue, and in each case a poor helix forming residue, glycine, is replaced by a residue with a higher helical propensity. We also present data showing that one revertant, Tyr22 → Phe, has reduced operator DNA binding affinity despite its enhanced stability.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology
- differential scanning calorimetry
- mutant repressors
- protein stability
- thermal denaturation