Increasing and decreasing protein stability: Effects of revertant substitutions on the thermal denaturation of phage λ repressor

Publisher Website
Google Scholar
Abstract
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.