International Summer School PROGRAM - Laboratoire d'Infochimie ...

Rigid Luminescent Bis-Zinc (II)–Bis-Cyclen Complexes and Non-
Covalent Protein Labelling in Aqueous Solution
Mouchumi Bhuyan,
Evgeny Katayev, Stefan Stadlbauer, Itaru Hamachi,
Burkhard König
The selective luminescent labelling of proteins by markers is an important quest and an
ongoing challenge in molecular biology. Covalent labelling uses reactive dyes or
genetic fusion of fluorescent proteins, for example, green fluorescent proteins (GFPs).
Non-covalent labelling strategies employ antibodies or snap tags. Recently a new high
II
affinity peptide tag – artificial probe pair orthogonal to the His tag– Ni –NTA pair has
been developed by Hamachi group for protein labeling, employing coordination
chemistry and multivalent interaction between a genetically encodable oligoaspartate
sequence (D4-tag) and a corresponding oligonuclear Zn II –Dpa complex. Because
artificial zinc dipicolylamine (Zn II –Dpa) receptors and zinc-1,4,7,10-
tetraazacyclododecane (Zn II –cyclen) complex derivatives are both known for their
application as phosphate binders under physiological conditions, we considered using
Zn II –cyclen derivatives as alternative artificial probes for the developed artificial probes
for oligoaspartate (D4- tag) and oligoglutamate (E4-tag) tag sequences. Although the
coordination geometry of Zn II –Dpa and Zn II –cyclen is rather different, Zn II –cyclen
derivatives show a comparable high binding affinity and fluorescence response and may
therefore be used as an alternative artificial non-covalent protein marker. The binding
affinity studies of the synthesized receptors to the genetically encodable tag proteins
will be presented in detail. i
i M. Bhuyan, E. Katayev, S. Stadlbauer, H. Nonaka, A. Ojida, I. Hamachi, B. König, Eur. J. Org. Chem.
2011, 2807–2817