[Protein Folding and Stability in the Presence of Osmolytes].

Osmolytes are molecules with the function among others to align hydrostatic pressure between intracellular and extracellular spaces. Accumulation of osmolytes occurs in the cell in response to stress caused by pressure change, change in temperature, pH, and concentration of inorganic salts. Osmolytes can prevent native proteins denaturation and promote folding of unfolding proteins. Investigation of the osmolytes effect on these processes is essential for understanding the mechanisms of folding and functioning of proteins in vivo. A score of works, devoted to the effect of osmolytes on proteins, are not always consistent with each other. In this review an attempt was made to systemize available array of data on the subject and consider the problem of folding and stability of proteins in solutions in the presence of osmolytes from the single viewpoint.

[Physical-chemical properties of the mutant (protein) form of D-glucose/D-galactose-binding protein GGBP/H152C with an attached fluorescent dye BADAN].

The influence of various factors on the physico-chemical characteristics and complexation of glucose with a mutant form of D-glucose/D-galactose-binding protein which can be regarded as a sensor of the glucometer, namely the protein GGBP/H152C with solvatochromic dye BADAN attached to the cysteine residue Cys 152, has been investigated. The point mutation His 152Cys and attaching BADAN reduced the affinity of the mutant form GGBP/H152C to glucose more than 8-fold compared to the wild type protein. This allows using this mutant for the determination of sugar content in biological fluids extracted by transdermal technologies. Sufficiently rapid complexation of GGBP/H152C with glucose (the time of protein-glucose complex formation is not more than three seconds even in solutions with a viscosity of 4 cP) provides timely monitoring changes in the concentration of sugar. The changes of ionic strength and pH within the physiological range of values of these variables do not have significant influence on fluorescent characteristics of GGBP/H152C-BADAN. At acidic pH, (see symbol) some of the molecules GGBP/H152C is in the unfolded state. It has been shown that mutant form GGBP/H152C has relatively low resistance to guanidine hydrochloride denaturing effects. This result indicates the need for more stable proteins to create a sensor for glucose biosensor system.

[Interaction between non-histone chromatin protein HMGB1 and linker histone H1].

The fundamental possibility of interaction between non-histone chromatin protein HMGB1 and linker histone H1 was studied in the solutions with different ionic strength by intrinsic UV-fluorescence, far and near-UV CD and spectrophotometry. The obtained data allow us to assume that the increase of histone H1 content in the HMGB1 solutions in a low ionic strength is accompanied by the destruction of HMGB1 associates. The interaction between proteins of HMGB1 and H1 causes the increase in the number of ordered regions in the protein molecules and the minor changes in their tertiary structure.

[Stability of sugar-binding proteins: D-galactose/D-glucose-binding protein from Escherichia coli and trehalose/maltose-binding protein from Thermococcus litoralis].

In this work we studied the structure and stability of sugar-binding proteins from mesophilic and thermophilic organisms which are of great importance for their possible use as sensing probe of biosensors aimed to glucose detection in the blood. The data obtained revealed the stabilizing effect of ligands on the structures of D-galactose/D-glucose-binding protein (GGBP) from Escherichia coli and trehalose/maltose-binding protein from thermophilic bacterium Thermococcus litoralis. It was found that TMBP possess an increased stability as its structure remains native even under heating up to 95 degrees C.