Biotinamidohexanoyl-6-aminohexanoic acid N-hydroxysuccinimide ester has been used in human IgM biotinylation.
Biotinylation reagent incorporating an extended 14-atom spacer can reduce steric hindrance in binding avidin or streptavidin to some biotinylated compounds and increase sensitivity for detection. Typically coupled to primary amine in the pH range 6.5-8.5.