Synthetic immunoglobulin domains with binding properties engineered in regions of the molecule different from the complementarity determining regions
Libraries of immunoglobulins which each have one or more amino acid modifications in at least one structural loop region of such immunoglobulins, where the modified loop region specifically binds to an epitope of an antigen to which an unmodified immunoglobulin does not significantly bind.
1. A library of immunoglobulin comprising human IgG1 CH3 domains, each of said CH3 domains comprising two or more structural loop regions, wherein at least two of said two or more structural loop regions together comprises at least three amino acid modifications with respect to the corresponding wild type structural loop regions of said CH3 domain, and thereby form a solvent accessible surface absent from the corresponding wild type structural loop regions of said CH3 domain, wherein the modified loop regions are within an amino acid sequence selected from the group consisting of amino acids 7 to 21, amino acids 25 to 39, amino acids 41 to 81, amino acids 83 to 85, amino acids 89 to 103, and amino acids 106 to 117, wherein the numbering is according to the IMGT, wherein the library comprises at least 100 immunoglobulins comprising different modified loop regions of said CH3 domain, wherein said amino acid modification is selected from the group consisting of an amino acid substitution, an addition of one or more amino acids, a loss of an amino acid and a combination thereof, and wherein said modification does not encompass insertion of a peptide of predetermined sequence that specifically binds a ligand independently of its insertion into said at least two structural loop regions.
2. The library of claim 1 , wherein the library consists of at least 1,000 immunoglobulins.
3. The library of claim 1 , wherein the library consists of at least 10,000 immunoglobulins.
4. The library of claim 1 , wherein the immunoglobulin is displayed on the surface of a host.
5. The library according to claim 4 , wherein the host is selected from the group consisting of mammalian cells, bacterial cells, insect cells, and yeast cells.
6. The library according to claim 1 , wherein the immunoglobulin is displayed on the surface of phages, phagemids or viruses.
7. The library according to claim 1 , wherein the immunoglobulin is displayed by an in vitro display technology.
8. The library according to claim 7 , wherein the in vitro technology is selected from the group consisting of polysome display, mRNA display, and ribosome-inactivation display.
9. The library of claim 1 , wherein up to thirty amino acids are modified.