Methods and compositions for prolonging elimination half-times of bioactive compounds
Peptide ligands having affinity for IgG or for serum albumin are disclosed. Also disclosed are hybrid molecules comprising a peptide ligand domain and an active domain. The active domain may comprise any molecule having utility as a therapeutic or diagnostic agent. The hybrid molecules of the invention may be prepared using any of a number techniques including production in and purification from recombinant organisms transformed or transfected with an isolated nucleic acid encoding the hybrid molecule, or by chemical synthesis of the hybrid. The hybrid molecules have utility as agents to alter the elimination half-times of active domain molecules. Elimination half-time is altered by generating a hybrid molecule of the present invention wherein the peptide ligand has binding affinity for a plasma protein. In a preferred embodiment, a bioactive molecule having a short elimination half-time is incorporated as or into an active domain of the hybrid molecules of the invention, and the binding affinity of the peptide ligand domain prolongs the elimination half-time of the hybrid as compared to that of the bioactive molecule.
1. A peptide ligand comprising a non-naturally occurring amino acid sequence, wherein the amino acid sequence is Xaa i -Cys-Xaa j -Cys-Xaa k that binds IgG-Fc, wherein Xaa is any amino acid, Xaa i is 0-4 amino acids, Xaa j is Xaa-Xaa-Xaa-Xaa-Xaa-Xaa-Leu -Val-Trp (SEQ ID NO:9), and Xaa k is 0-5 amino acids.
2. The peptide ligand of claim 1 wherein Xaa j is Xaa-Xaa-Xaa -Xaa-Gly-Glu-Leu-Val-Trp (SEQ ID NO: 10).
3. The peptide ligand of claim 2 wherein Xaa j is Xaa 1 -Xaa 2 -Xaa 3 -Xaa 4 -Gly-Glu-Leu-Val-Trp-Cys (SEQ ID NO: 10) and Xaa 1 is Ala, Ser, or Thr, Xaa 2 is Trp or Tyr, Xaa 3 is His, or Trp, and Xaa 4 is Leu or Met.
4. The peptide ligand of claim 1 or claim 2 comprising the amino acid sequence Xaa-Xaa-Xaa-Xaa-Cys-Xaa-Xaa-Xaa-Xaa-Xaa-Xaa-Leu-Val-Trp-Cys -Xaa-Xaa-Xaa-Xaa-Xaa (SEQ ID NO:11) wherein Xaa is any amino acid.
5. The peptide ligand of claim 4 comprising the amino acid sequence Xaa-Xaa-Xaa-Xaa-Cys-Xaa-Xaa-Xaa-Xaa-GIy-Glu-Leu-Val-Trp-Cys-Xaa-Xaa-Xaa -Xaa-Xaa (SEQ ID NO: 12).
6. The peptide ligand of claim 5 comprising the amino acid sequence Xaa 1 -Xaa 2 -Xaa 3 -Xaa 4 -Cys-Xaa 5 -Xaa 6 -Xaa 7 -Xaa 8 -Gly-Glu-Leu-Val-Trp-Cys-Xaa 9 -Xaa 10 -Xaa 11 -Xaa 12 -Xaa 13 (SEQ ID NO:13), wherein Xaa 5 is Ala, Ser, or Thr, Xaa 6 is Trp or Tyr, Xaa 7 is His, or Trp, Xaa 8 is Leu or Met, and Xaa 1-4 and 9-13 are each an amino acid.
7. The peptide ligand of claim 6 wherein Xaa 4 is Ser, Arg, or Asp; Xaa 5 is Ala, Ser, or Thr; Xaa 6 is Trp or Tyr; Xaa 7 is His or Trp; Xaa 8 is Leu or Met; and Xaa 9 is Glu, Ser, Thr or Val (SEQ ID NO: 14).
8. The peptide of claim 1 wherein the peptide ligand comprises the amino acid sequence DCAWHLGELVWCT (SEQ ID NO:8).
9. The peptide ligand of claim 1 , wherein the amino acid sequence is cyclized by the presence of disulfide-bonded Cys residues.
10. The peptide ligand of claim 1 , wherein the peptide ligand is less than 50 amino acid residues.
11. The peptide ligand of claim 1 , wherein the peptide ligand is less than 40 amino acid residues.
12. The peptide ligand of claim 1 , wherein the peptide ligand is between 10 and 30 amino acid residues.
13. The peptide ligand of claim 1 , wherein the peptide ligand has an IC 50 for IgG-Fc of less than about 1 μM.
14. The peptide ligand of claim 1 , wherein the peptide ligand has an IC 50 for IgG-Fc of less than about 100 nM.
15. The peptide ligand of claim 1 , wherein the peptide ligand is non-covalently adsorbed or covalently bound to a macromolecule.
16. The peptide ligand of claim 15 , wherein the macromolecule is a solid support.
17. The peptide ligand of claim 1 , wherein the peptide ligand is labeled with a detectable moiety.