Immunoglobulin variable domains
VH domain, in which: (i) the amino acid residue at position 112 is one of K or Q; and/or (ii) the amino acid residue at position 89 is T; and/or (iii) the amino acid residue at position 89 is L and the amino acid residue at position 110 is one of K or Q; and (iv) in each of cases (i) to (iii), the amino acid at position 11 is preferably V; and in which said VH domain contains a C-terminal extension (X)n, in which n is 1 to 10, preferably 1 to 5, such as 1, 2, 3, 4 or 5 (and preferably 1 or 2, such as 1); and each X is an (preferably naturally occurring) amino acid residue that is independently chosen, and preferably independently chosen from the group consisting of alanine (A), glycine (G), valine (V), leucine (L) or isoleucine (I).
1. Heavy-chain immunoglobulin single variable domain, in which the amino acid residue at position 112 is K or Q, wherein amino acid residue positions in the heavy-chain immunoglobulin single variable domain are indicated with the numbering according to Kabat.
2. The heavy-chain immunoglobulin single variable domain according to claim 1 , that has a C-terminal sequence (positions 109 to 113 according to Kabat) that is VTVKS (SEQ ID NO:1) or VTVQS (SEQ ID NO:2), or a sequence that has one amino acid difference at one of the positions 109, 110, 111 or 113 with either the sequence VTVKS and/or VTVQS and that still has either the amino acid residue K or Q at position 112.
3. The heavy-chain immunoglobulin single variable domain according to claim 1 , that contains an amino acid residue at position 11 that is chosen from L, E, K, V and Y, wherein amino acid residue positions in the heavy-chain immunoglobulin single variable domain are indicated with the numbering according to Kabat.
4. The heavy-chain immunoglobulin single variable domain according to claim 1 , in which the amino acid residue at position 11 is E and the amino acid residue at position 112 is K, wherein amino acid residue positions in the heavy-chain immunoglobulin single variable domain are indicated with the numbering according to Kabat.
5. The heavy-chain immunoglobulin single variable domain according to claim 1 , in which the amino acid residue at position 108 is L, wherein amino acid residue positions in the heavy-chain immunoglobulin single variable domain are indicated with the numbering according to Kabat.
6. The heavy-chain immunoglobulin single variable domain according to claim 1 , that has a framework 4 (FW4 sequence) that is either:
a) one of the FW4 sequences of SEQ ID NOs: 3 to 5, 7 to 14, 16 to 20; or
b) a sequence that has no more than three amino acid differences with at least one of the FW4 sequences of SEQ ID NOs 3 to 5, 7 to 14, 16 to 20, in which the amino acid residue at the position corresponding to position 112 of the Kabat numbering is either K or Q.
7. The heavy-chain immunoglobulin single variable domain according to claim 6 , that has a framework 4 (FW4 sequence) that is either:
a) WGQGTQVTVKS (SEQ ID NO:3) or WGQGTQVTVQS (SEQ ID NO:12); or
b) a sequence that has no more than three amino acid differences with SEQ ID NO:3 and/or SEQ ID NO: 12, in which the amino acid residue at the position corresponding to position 112 of the Kabat numbering is either K or Q.
8. The heavy-chain immunoglobulin single variable domain according to claim 1 , wherein the amino acid residue at position 113 is S, T, A, L, P, F, E, or V, wherein amino acid residue positions in the heavy-chain immunoglobulin single variable domain are indicated with the numbering according to Kabat.
9. The heavy-chain immunoglobulin single variable domain according to claim 1 , which can specifically bind to human serum albumin.
10. The heavy-chain immunoglobulin single variable domain according to claim 9 , which has at least 80% sequence identity with at least one of Alb-1 (SEQ ID NO: 767), Alb-8 (SEQ ID NO: 46) and/or Alb-23 (SEQ ID NO:61).
11. The heavy-chain immunoglobulin single variable domain according to claim 9 , in which:
CDR1 is the amino acid sequence SFGMS (SEQ ID NO:41);
CDR2 is the amino acid sequence SISGSGSDTLYADSVKG (SEQ ID NO:42); and
CDR3 is the amino acid sequence GGSLSR (SEQ ID NO:43).
12. The heavy-chain immunoglobulin single variable domain according to claim 1 , that is linked at its C-terminal end to another amino acid sequence, moiety, domain or binding unit, optionally via a suitable linker.
13. The heavy-chain immunoglobulin single variable domain according to claim 12 , that is linked at its C-terminal end to another immunoglobulin single variable domain, optionally via a suitable linker.
14. The heavy-chain immunoglobulin single variable domain according to claim 1 , that is linked, at its C-terminal end, to a C-terminal extension (X) n , in which n is 1 to 5; and each X is an amino acid residue that is independently chosen.
15. The heavy-chain immunoglobulin single variable domain according to claim 1 , that is a VHH domain, a humanized VHH domain or a camelized VH domain.
16. Protein, polypeptide, construct, compound or other chemical entity that comprises at least one heavy-chain immunoglobulin single variable domain according to claim 1 .
17. The protein, polypeptide or compound according to claim 16 , that comprises at least two heavy-chain immunoglobulin single variable domains, either linked directly or via a suitable linker.
18. A composition comprising the heavy-chain immunoglobulin single variable domain according to claim 1 and at least one pharmaceutically acceptable carrier, diluent or excipient.
19. The heavy-chain immunoglobulin single variable domain according to claim 1 , that is linked, at its C-terminal end, to a C-terminal extension (X) n , in which n is 1 to 5; and each X is an amino acid residue that is independently chosen from the group consisting of alanine (A), glycine (G), valine (V), leucine (L) and isoleucine (I).