Disclosed is a method of engineering an immunobinder, the immunobinder comprising a human Vlambda1 family light chain variable region, or fragment thereof, the Vlamda1 family light chain variable region comprising VL framework residues, the method comprising: A) selecting one or more amino acid positions within the Vlambda1 framework residues and B) mutating the one or more amino acid positions selected for mutation, wherein the mutating comprises one or more substitutions selected from the group consisting of: wherein if the one or more light chain amino acid positions selected for mutation are of a human Vlambda1 family light chain variable region, the mutating comprises one or more substitutions selected from the group consisting of: (i) leucine (L), serine (S) or glutamic acid (E) at amino acid position 1 using AHo or Kabat numbering system (ii) alanine (A), proline (P), isoleucine (I) or tyrosine (Y) at amino acid position 2 using AHo or Kabat numbering system (iii) valine (V) or methionine (M) at amino acid position 4 using AHo or Kabat numbering system (iv) glutamic acid (E) at amino acid position 7 using AHo or Kabat numbering system (v) alanine (A) at amino acid position 11 using AHo or Kabat numbering system (vi) threonine (T) or serine (S) at amino acid position 14 using AHo or Kabat numbering system (vii) histidine (H) at amino acid position 46 using AHo numbering system (amino acid position 38 using Kabat numbering system) (viii) threonine (T), serine (S), asparagine (N), glutamine (Q) or proline (P) at amino acid position 53 using AHo numbering system (amino acid position 45 using Kabat numbering system) (ix) arginine (R) or glutamine (Q) at amino acid position 82 using AHo numbering system (amino acid position 66 using Kabat numbering system) (x) glycine (G), threonine (T) or aspartic acid (D) at amino acid position 92 using AHo numbering system (amino acid position 74 using Kabat numbering system) and (xi) valine (V), threonine (T), histidine (H) or
