| Abstrakt: |
The thermal denaturations of five revertant lambda 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 degrees C more stable than wild type. These two substitutions replace an alpha 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. |
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