Osmium tetroxide, 2,2'-bipyridine (Os,bipy): Electroactive marker for probing accessibility of tryptophan residues in proteins.

Osmium tetroxide complexes (Os,L) belong to traditional tools developed and applied by DMCMO in studies of DNA structure and in DNA labeling, based on facile covalent modification of unpaired thymine residues by the Os,L reagents. Besides thymine and other pyrimidines, covalent adducts with Os,L are formed under physiological conditions also with tryptophan residues, making it applicable in probing proteins structure. As a proof of principle, Os,bipy was used here to study reactivity of tryptophan residues in avidin a streptavidin and their complexes with biotin.

M. Fojta, S. Billova, L. Havran, H. Pivonkova, H. Cernocka, P. Horakova, and E. Palecek, Osmium tetroxide, 2,2 '-bipyridine: Electroactive marker for probing accessibility of tryptophan residues in proteins. Analytical Chemistry 80, 4598-4605, 2008.