The promising direction of the development of a modern glucometer is the construction of sensing
element on the basis of stained (dyed) protein which changes its fluorescence upon glucose binding.
One of the proteins that can be used for this purpose is the D-trehalose/D-maltose-binding protein (TMBP)
from the thermophilic bacteria Thermococcus litoralis. We investigated the physical–chemical properties
of the protein and evaluated its stability to the denaturing action of GdnHCl and heating. It was confirmed
that TMBP is an extremely stable protein. In vivo, the intrinsic ligands of TMBP are trehalose and maltose,
but TMBP can also bind glucose. The dissociation constant of the TMBP–glucose complex is in the range of
3–8 mM. The binding of glucose does not noticeably change the intrinsic fluorescence of the TMBP. To
register protein-glucose binding, we used the fluorescence of the thiol-reactive dye BADAN attached to
TMBP. Because the fluorescence of BADAN attached to the cysteine Cys182 of TMBP does not change upon
glucose binding, the mutant forms TMBP/C182S/X_Cys were created. In these mutant proteins, Cys182 is
replaced by Ser, removing intrinsic binding site of BADAN and a new dye binding sites were introduced.
The largest increase (by 1.4 times) in the intensity of the dye fluorescence was observed upon TMBP/
C182S/A14C-BADAN–Glc complex formation. The dissociation constant of this complex is 3.4 ± 0.1 mM.
We consider TMBP/C182S/A14C mutant form with attached fluorescent dye BADAN as a good basis for
further research aimed to develop of series of TMBP mutant forms with different affinities to glucose
labeled with fluorescent dyes.