Immunoglobulin variable domains

Abstract

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 .- 72 . (canceled) 
     
     
         73 . A nucleic acid encoding a heavy chain ISVD or a polypeptide comprising said ISVD, wherein said ISVD comprises:
 (i) an amino acid K or Q at Kabat position 110; and   (ii) an amino acid V at Kabat position 11, an amino acid residue L at Kabat position 89, or a combination thereof.   
     
     
         74 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises the amino acid V at position 11, optionally further comprising an amino acid at Kabat position 89 that is T, V, or L. 
     
     
         75 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises the amino acid L at position 89, optionally further comprising an amino acid at Kabat position 11 that is L, E, K, V, or Y. 
     
     
         76 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises the amino acid V at Kabat position 11 and the amino acid L at Kabat position 89. 
     
     
         77 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises the amino acid K at Kabat position 110, the amino acid V at Kabat position 11 and the amino acid L at Kabat position 89. 
     
     
         78 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises an amino acid selected from the group consisting of A and P at Kabat position 14. 
     
     
         79 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises an amino acid selected from the group consisting of A and P at Kabat position 41. 
     
     
         80 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises an amino acid selected from the group consisting of Q, L, R, P, E, K, S, T, M, A, and H at Kabat position 108. 
     
     
         81 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises an amino acid selected from Q and L at Kabat position 108. 
     
     
         82 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises an amino acid selected from the group consisting of S, T, A, L, P, F, E, and V at Kabat position 113. 
     
     
         83 . The nucleic acid of claim  72 , wherein the heavy chain ISVD comprises a C-terminal extension (X) n , in which n is 1 to 10, wherein each X is an independently chosen amino acid. 
     
     
         84 . The nucleic acid of  claim 83 , wherein each X is an amino acid independently chosen from the group consisting of A, G, V, L, and I. 
     
     
         85 . The nucleic acid of claim  72 , wherein the C-terminal end of the heavy-chain ISVD comprises an amino acid sequence selected from the group consisting of: VKVSS (SEQ ID NO: 95), VKVSS(X) n  (SEQ ID NO:97), VQVSS (SEQ ID NO: 96), VQVSS(X) n  (SEQ ID NO: 98), VZVZS (SEQ ID NO: 107), in which each amino acid residue Z is independently K or Q), and VZVZS(X) n  (SEQ ID NO:108), in which each amino acid residue Z is independently K or Q), in which n is 1 to 10, wherein each X is an independently chosen amino acid. 
     
     
         86 . The nucleic acid of  claim 85 , wherein each X is an amino acid independently chosen from the group consisting of A, G, V, L, and I. 
     
     
         87 . The nucleic acid of claim  72 , wherein the heavy chain ISVD is a VHH domain, a humanized VHH domain, or a camelized VH domain. 
     
     
         88 . A library comprising one or more nucleic acids according to claim  72 . 
     
     
         89 . The library of  claim 88 , wherein the library comprises at least 100 different sequences. 
     
     
         90 . A library of heavy chain ISVDs according to claim  72 . 
     
     
         91 . The library according to  claim 88 , which is an expression library. 
     
     
         92 . The library according to  claim 88 , which is a synthetic library. 
     
     
         93 . A method for producing a heavy chain ISVD comprising expressing the nucleic acid according to claim  72  in a suitable host organism.