Collection of repeat proteins comprising repeat modules

1. A collection of nucleic acid molecules encoding a collection of repeat proteins, each repeat protein comprising a repeat domain, which comprises a set of consecutive repeat modules,

wherein each of said repeat modules is derived from one or more repeat units, wherein said repeat units are ankyrin repeats and wherein said repeat units comprise framework residues, which contribute to the folding topology of said repeat unit or contribute to an interaction with a neighboring repeat unit, and target interaction residues, which contribute to an interaction with a target substance,

wherein said repeat proteins differ from other repeat proteins in said collection in at least one amino acid position of the repeat modules, and

wherein said derivation of each of said repeat modules is carried out by an analysis comprising the steps of

(a) identifying said repeat units;

(b) determining a repeat sequence motif by structural and sequence analysis of said repeat units,

wherein said structural and sequence analysis includes the identification of said framework residues and said target interaction residues of said repeat units; and

(c) constructing the repeat module so that it comprises the repeat sequence motif of (b).

2. The collection of claim 1 , wherein each of said repeat modules has an amino acid sequence, wherein at least 70% of the amino acid residues are either

(i) consensus amino acid residues deduced from the amino acid residues found at the corresponding positions on alignment of at least two repeat units; or

(ii) the amino acid residues found at the corresponding positions in a repeat unit.

3. The collection of claim 1 , wherein said set consists of between two and about 30 repeat modules.

4. The collection of claim 1 or 3 , wherein said repeat modules are directly connected without an intervening amino acid sequence.

5. The collection of claim 1 or 3 , wherein said repeat modules are connected by a peptide or polypeptide linker.

6. The collection of claim 1 or 3 , wherein said repeat domain further comprises an N- and/or a C-terminal capping module having an amino acid sequence different from any one of said repeat modules.

7. The collection of claim 1 , wherein said set consists of one type of repeat modules of the same length of said module and consisting of the same number and composition of the fixed amino acid positions.

8. The collection of claim 1 , wherein said set consists of two different types of repeat modules, wherein each said type of repeat module is of the same length and consists of the same number and composition of the fixed amino acid positions, and wherein said two different types differ in at least the length or the number or the composition of the fixed amino acid positions.

9. The collection of claim 1 , wherein said set comprises in said repeat domain a pair of two different types of consecutive repeat modules wherein each said type of repeat module is of the same length and consists of the same number and composition of the fixed amino acid positions, wherein said two different types differ in at least the length or the number or the composition of the fixed amino acid positions.

10. The collection of claim 1 , wherein each of said repeat modules comprises the ankyrin repeat sequence motif

D11G1TPLHLAA11GHLEIVEVLLK2GADVNA1, (SEQ ID NO: 4)

wherein 1 represents an amino acid residue selected from the group:

A, D, E, F, H, I, K, L, M, N, Q, R, S, T, V, W and Y;

wherein 2 represents an amino acid residue selected from the group:

H, N and Y.

11. The collection of claim 10 , wherein the collection comprises nucleic acids generated by exchange of nucleotides such that one or more of the amino acid residues in said consensus sequences are replaced by an amino acid residue found at the corresponding position on alignment of a repeat unit.

12. The collection of claim 1 , 3 or 10 , wherein said nucleic acid molecules comprise identical nucleic acid sequences of at least 9 nucleotides between said repeat modules.

13. The collection of claim 12 , wherein said identical nucleic acid sequences allow assembly of said nucleic acid molecules by PCR technology.

14. The collection of claim 1 , 3 or 10 , wherein there are nucleic acid sequences between said modules, and each of said nucleic acid sequences between said modules comprises a restriction enzyme recognition sequence.

15. The collection of claim 1 , 3 or 10 , wherein there are nucleic acid sequences between said repeat modules and each of said nucleic acid sequences between said repeat modules comprises a nucleic acid sequence formed from cohesive ends created by two restriction enzymes.

16. A collection of recombinant nucleic acid molecules comprising a collection of nucleic acid molecules according to claim 1 , 3 or 10 .