Collections of repeat proteins comprising repeat modules

1. A collection of repeat proteins, each repeat protein comprising a repeat domain, which comprises two or more consecutive repeat modules,

wherein said repeat modules have the same fold and stack tightly to create a superhelical structure having a joint hydrophobic core,

wherein each of said repeat modules is derived from one or more repeat units 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 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 , wherein said repeat modules are directly connected without an intervening amino acid sequence.

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

6. The collection of claim 1 , 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 repeat units are ankyrin repeats.

8. The collection of claim 7 , wherein each of said repeat modules comprises the ankyrin repeat sequence motif

D 11 G 1 TPLHLAA 11 GHLEIVEVLLK 2 GADVNA 1 ,

(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.

9. The collection of claim 8 , wherein one or more of the amino acid residues in said sequence motif is replaced by an amino acid residue found at the corresponding position on alignment of a repeat unit.