Rational design of an active avidin monomer

Olli H. Laitinen, Henri R. Nordlund, Vesa P. Hytönen, Sanna T.H. Uotila, Ari T. Marttila, Janne Savolainen, Kari J. Airenne, Oded Livnah, Edward A. Bayer, Meir Wilchek, Markku S. Kulomaa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Homotetrameric chicken avidin that binds four molecules of biotin was converted to a monomeric form (monoavidin) by mutations of two interface residues: tryptophan 110 in the 1 → 2 interface was mutated to lysine and asparagine 54 in the 1 → 4 interface was converted to alanine. The affinity for biotin binding of the mutant decreased from Kd ∼10-15 M of the wild-type tetramer to Kd ∼10-7 M, which was studied by an optical biosensor IAsys and by a fluorescence spectroscopical method in solution. The binding was completely reversible. Conversion of the tetramer to a monomer results in increased sensitivity to proteinase K digestion. The antigenic properties of the mutated protein were changed, such that monoavidin was only partially recognized by a polyclonal antibody whereas two different monoclonal antibodies entirely failed to recognize the avidin monomer. This new monomeric avidin, which binds biotin reversibly, may be useful for applications both in vitro and in vivo. It may also shed light on the effect of intersubunit interactions on the binding of ligands.

Original languageAmerican English
Pages (from-to)4010-4014
Number of pages5
JournalJournal of Biological Chemistry
Issue number6
StatePublished - 7 Feb 2003


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