Patent ID: 9499580
Filing Date: 2016-11-22
CPC Classification: C07K,C12N,G16B

Claim Text:
1. A method of engineering a pH sensitive conformational switch in a protein that is not a staphylococcal nuclease, the method comprising: i) selecting a protein that has a minimum initial thermodynamic stability of 12 kcal/mol per pH unit at 298 K to tolerate the energetic cost of substituting one or more amino acid residues in the interior of a protein with a destabilizing ionizable group; ii) selecting one or more amino acid residues in the interior of the protein whose substitution with one or more ionizable amino acid residues would cause the protein to switch conformation in response to small changes in pH; and iii) substituting the selected one or more amino acid residues in the interior of the protein with one or more ionizable amino acid residues to form a pH sensitive conformational switch in the protein in which the one or more ionizable amino acid residues titrate with a pKa value shifted relative to the normal pKa value in water for the one or more ionizable amino acid residues, the protein is fully folded under conditions of pH in which the internal ionizable amino acid residues are charged, and the protein switches conformation in response to small changes in pH.