Methods for stabilizing proteins
The present inventors revealed that deamidation of an antibody can be suppressed without influencing its activity by substituting a glycine that is located adjacent to an asparagine with another amino acid.
1. A method for generating a nucleic acid encoding a mutant antibody, the method comprising:
(a) identifying an antibody that is susceptible to deamidation, wherein the antibody includes a first region that is a complementarity determining region (CDR);
(b) identifying an asparagine residue susceptible to deamidation within the first region;
(c) identifying a glycine residue located adjacent and C-terminal to the asparagine residue; and
(d) producing a recombinant nucleic acid molecule that encodes a mutant antibody, wherein the mutant antibody is identical to the antibody of (a) except for an alteration selected from the group consisting of (i) a deletion of the glycine residue, and (ii) a substitution of the glycine residue with an amino acid residue other than valine, isoleucine or proline,
wherein the mutant antibody of (d) is less susceptible to deamidation than is the antibody of (a), and wherein the mutant antibody of (d) exhibits at least 70% of the antigen binding activity exhibited by the antibody of (a).
2. The method of claim 1 , wherein the mutant antibody is a humanized antibody.
3. The method of claim 1 , wherein the CDR is CDR2.
4. A method for generating a mutant antibody, the method comprising providing a host cell harboring a recombinant nucleic acid produced by the method of claim 1 , and expressing the mutant antibody in the host cell.
5. The method of claim 4 , further comprising the step of formulating the mutant antibody into a pharmaceutical composition.
6. The method of claim 1 , further comprising:
(e) expressing the mutant antibody encoded by the recombinant nucleic acid of (d); and
(f) comparing the antigen binding activity of the antibody of (a) with the antigen binding activity of the mutant antibody of (e).
7. The method of claim 6 , further comprising:
(g) comparing the stability over time of the antibody of (a) to the stability of the mutant antibody of (e).
8. The method of claim 1 , further comprising:
(e) expressing the mutant antibody encoded by the recombinant nucleic acid of (d); and
(f) comparing the stability over time of the antibody of (a) to the stability of the mutant antibody of (e).
9. The method of claim 1 , wherein the mutant antibody of (d) exhibits at least 80% of the antigen binding activity exhibited by the antibody of (a).
10. The method of claim 1 , wherein the mutant antibody of (d) exhibits at least 90% of the antigen binding activity exhibited by the antibody of (a).