Patent ID: 8759488
Filing Date: 2014-06-24
Classification: C07K

Abstract:
1. A mutant streptavidin subunit which comprises one or more amino acid substitutions compared to a wildtype streptavidin subunit at any one or more of residue positions equivalent to positions 52, 53, 50, 51 and 54 of SEQ ID NO: 2 and wherein amino acid residues at positions equivalent to positions 23, 27, 43, 45, 49, 79, 88, 90, 92, 108, 110 and 128 of SEQ ID NO: 2 , in said mutant streptavidin subunit, are wildtype, wherein (i) when said mutant streptavidin subunit is in a streptavidin tetramer, said streptavidin has a lower off rate for biotin or for a biotin conjugate than wildtype streptavidin, or (ii) when said mutant streptavidin subunit is in monomeric form, said mutant monomeric streptavidin has a lower off rate for biotin or a biotin conjugate than monomeric streptavidin, and wherein the amino acid residue at the position equivalent to position 52 of SEQ ID NO. 2 is substituted with glycine and the amino acid residue at the position equivalent to position 53 of SEQ ID NO. 2 is substituted with aspartic acid.