We have found calcium-modulated electrostatic interactions between monomeric ?-lactalbumin and histon HIII and model poly-amino acids polyLys and polyArg. The interactions seem to be the reason of the anti-tumor effects of some forms of ?-lactalbumin. Physico-chemical properties of the complex of ?-lactalbumin with the histon have been studied.
We have revealed a new state of ?-lactalbumin in the complexes with poly-Lys, poly-Arg and histons, which are characterised by low thermal stability and low calcium affinity (LAMPA).
We have developed a new method for studies of metal binding properties of single-site proteins - a construction of state diagrams in the coordinates free calcium concentration - temperature.
It has been shown that apo-parvalbumins refer to the family of natively disordered proteins.
We have found that the thermal denaturation of the highly thermostable Ca2+-loaded form of parvalbumins is described by a model of two sequential first order thermal transitions ascribed to an unfolding of two cooperative domains.
The thermal denaturation of Mg2+- and Na+-loaded parvalbumins is described by a single two-state first order transition.
It has been revealed that universal enzymatic modification of proteins, common for eucariots, N-terminal acetylation, is important for maintenance of structural and functional status of some parvalbumins.
Phase diagrams in temperature – free Ca2+/Mg2+ concentration co-ordinates were constructed for the ?-lactalbumin – lysozyme protein family. It has been found that Ca2+ и Mg2+ compete for the same strong calcium-binding site in ?-lactalbumin, while the main magnesium-binding site in lysozyme dos not coinside with the strong calcium-binding site in this protein.
We have shown that the formation of complexes of ?-lactalbumin with oleic acid depends on calcium concentration, ionic strength and temperature.
The complex of ?-lactalbumin with oleic acid formed in solution possesses physico-chemical, structural and cytotoxic properties, which are similar to those of the HAMLET state.
A novel express large-scale method for preparation of cytotoxic complexes of ?-lactalbumin with oleic acid possessing an antitumor and antibacterial HAMLET-like activity has been developed. The developed method is suited for development of other protein complexes other low-molecular-weight amphiphilic substances with valuable cytotoxic properties.
Oleic acid complexes with parvalbumin and ?-lactoglobulin possessing cytotoxic activity against tumor and Streptococcus pneumonia cells were obtained. Their activity was higher than that for HAMLET. It has been clearly demonstrated that the principal cytotoxic component of such complexes is oleic acid.
Using the properties of amino acid sequences of natively disordered regions, which can be ordered in the presence of partners, we have developed an algorithm of predictions of location of sites of protein-protein interactions.
Methods of bioinformatic analysis and search for intrinsically disordered regions were applied to the family of calcium binding proteins S100. It has been found that intrinsic disorder is characteristic for many S100 proteins and is important for their functional activity and functional diversity of the S100 protein family.
We have revealed totally or fragmentary natively disordered proteins, which can specifically interact with a large number of partners. Same natively disordered region can have absolutely different structure depending of complementary structure of the binding site of the target protein.
A novel method for prediction of intrinsic disorder in proteins, evaluation of global intrinsic disorder in various proteoms has been developed. It has been revealed an important role of proteins intrinsic disorder in various diseases and protein-protein interactions.
It has been revealed a relationship between disfolding and aggregation of ?-synuclein and Parkinson disease development. Copper ions essentially accelerate the process of ?-synuclein fibrillation.
To elucidate the role of intrinsic disorder in functioning of S100 proteins family, the combination of per-residue and binary disorder predictors has been applied to S100 proteome. 62% of proteins are predicted to be disordered by at least one of the predictors. Of them 31% are recognized as 'molten globules' and 15% shown to be extensively disordered.
The disordered part of the hinge and N-terminal half of the helix III in S100 are virtually not involved into dimerization, but are used solely for target recognition.
A separate rhodopsin kinase binding site has been found in the C-terminal part of recoverin, the calcium binding protein from rod outer segments.
An oxidation of the conservative Cys39 in recoverin has been found to be important for maintenance of the functional status of the protein. It has been suggested that Cys39 can serve as a redox-sensor in the vision system.