Biotin variant, streptavidin mutant, and uses thereof

The problem addressed by the present invention is: to provide a streptavidin mutant having a reduced affinity to natural biotin; and furthermore to provide a biotin variant that has a high affinity to the streptavidin mutant having reduced affinity to natural biotin. The present invention provides a compound comprising a biotin variant dimer, a streptavidin mutant, and uses thereof.