Functional heavy chain antibodies, fragments thereof, library thereof and methods of production thereof

Abstract

The present invention relates to functional heavy chain antibodies, functional single domain heavy chain antibodies, functional VH domains, or functional fragments thereof comprising an amino acid which is neither a charged amino acid nor a C at position 45, and comprising an amino acid at position 103 independently chosen from the group consisting of R, G, K, S, Q, L, and P, and optionally an amino acid at position 108 independently chosen from the group consisting of Q, L and R, said positions determined according to the Kabat numbering.

1 .- 41 . (canceled) 
     
     
         42 . A recombinant ligand comprising an immunoglobulin single variable domain, wherein said immunoglobulin single variable domain specifically binds serum albumin with an equilibrium dissociation constant (Kd) of less than or equal to 300 nM, as determined by surface plasmon resonance. 
     
     
         43 . The recombinant ligand of  claim 42 , wherein the Kd is less than 4 nM, as determined by surface plasmon resonance. 
     
     
         44 . The recombinant ligand of  claim 42 , wherein the Kd is in a range of 2 to 50 nM, as determined by surface plasmon resonance. 
     
     
         45 . The recombinant ligand of  claim 42 , wherein the immunoglobulin single variable domain is a heavy chain immunoglobulin single variable domain. 
     
     
         46 . The recombinant ligand of  claim 42 , wherein the immunoglobulin single variable domain specifically binds human serum albumin. 
     
     
         47 . The recombinant ligand of  claim 42 , wherein the ligand has improved stability relative to a ligand absent said immunoglobulin single variable domain that specifically binds serum albumin. 
     
     
         48 . A composition comprising the recombinant ligand of  claim 42 . 
     
     
         49 . A recombinant ligand consisting of an immunoglobulin single variable domain, wherein said immunoglobulin single variable domain specifically binds serum albumin with an equilibrium dissociation constant (Kd) of less than or equal to 300 nM, as determined by surface plasmon resonance. 
     
     
         50 . The recombinant ligand of  claim 49 , wherein the Kd is less than 4 nM, as determined by surface plasmon resonance. 
     
     
         51 . The recombinant ligand of  claim 49 , wherein the Kd is in a range of 2 to 50 nM, as determined by surface plasmon resonance. 
     
     
         52 . The recombinant ligand of  claim 49 , wherein the immunoglobulin single variable domain is a heavy chain immunoglobulin single variable domain. 
     
     
         53 . The recombinant ligand of  claim 49 , wherein the immunoglobulin single variable domain specifically binds human serum albumin. 
     
     
         54 . A polypeptide comprising the recombinant ligand of  claim 49 , wherein the polypeptide has improved stability relative to a polypeptide absent said immunoglobulin single variable domain that specifically binds serum albumin. 
     
     
         55 . A composition comprising the recombinant ligand of  claim 49 .