I. A. Sergeeva

Optical properties of solutions consisting of albumin and γ -globulin molecules in different ratio modeling blood serum

Rayleigh-Debye laser light scattering (RDLS) was used for study of the alterations of physical properties of albumin andγ-globulin molecules water solved in different ratios as a model system of blood serum. By using a portable optical device we simultaneously measured a number parameters of protein solutions such as the effective mass, coefficient of intermolecular interaction, diffusion coefficients of the components, etc. The results of the investigations for model systems were compared with the data obtained for blood serum of healthy and oncology patients.

The effect of lead cations on the fluorescence characteristics of bovine serum albumin in aqueous solution

The effect of lead (heavy metal) cations on the fluorescence characteristics and photophysical parameters (fluorescence intensity and anisotropy, absorption cross section, excited state lifetime, and rates of singlet-triplet conversion and reversible photobleaching) of tryptophan in an aqueous solution of bovine serum albumin (two-tryptophan protein) is studied and compared with the effect in the aqueous solution of tryptophan. It is demonstrated that the effect of lead on the fluorescence characteristics of the protein is manifested at a molar concentration ratio of metal cations and protein macromolecules of greater than 10 and related to the dynamic quenching of the excited state, protein aggregation, and an increase in the rate of singlet-triplet conversion (the effect of a heavy atom) in tryptophan molecules.

Effect of heavy-metal ions on dynamic characteristics of collagen molecules in solutions

Effect of heavy (Pb2+, Cs+) and light (Na+) metal ions on the molecular-dynamic characteristics of type-I collagen in aqueous solution was studied using the method of dynamic light scattering. It was found that the dependence of the translational diffusion coefficient Dt from pH solutions has a nonlinear form with a pronounced extremum close to the isoelectric point of the protein (pI 6.0). For pure aqueous solution of protein there is a maximum of Dt in isoelectric point. For collagen solutions with the addition of heavy-metal salts the minimum of Dt was observed near the isoelectric point. This fenomenon is connected with the formation of protein nanoclusters in solution. With concentration of heavy metal ions increasing translational diffusion coefficient Dt decreases, which shows on increasing of aggregation effect. The addition of sodium ions in aqueous solution of collagen containing heavy metal ions sharp decreasing of the translational diffusion of molecules is observed. That can be connected with the rise of scattering particles masses.

Interaction of albumin and γ-globulin molecules with gold nanoparticles in water solutions

The molecular mobility of scattering particles in water solutions of albumin and γ-globulin proteins with gold nanoparticles was investigated by the dynamic light scattering method. The dependences of translation diffusion coefficients of particles at various concentrations of the solution components have been obtained. It was revealed that in a wide range of concentrations of the solution components there is no interaction of gold nanoparticles with albumin, whereas gold nanoparticles form complexes with γ-globulin molecules.

Molecular mobility in protein solutions containing metal ions with various ionic radii

Using methods of photon-correlation spectroscopy and polarized fluorescence pH, the dependencies of the translation and rotary diffusion coefficients of collagen and bovine serum albumen in solutions on NaCl and KCl salts at various ion forces have been obtained. It is shown that the size of the metal ionic radius affects intermolecular interactions and the mobility of albumen molecules in solution. The effect of the potassium ion, with its large ionic radius, compared with Na ions, is analogous to the effect of heavy metals ions, since it results in albumen molecule aggregation near the isoelectric point.

Investigation of the molecular mobility of peptin macromolecules using photon-correlation spectroscopy

The pH dependence of the intermolecular interaction coefficient of pepsin in an aqueous solution is obtained by using photon-correlation spectroscopy. The dependence shows a minimum near the isoelectric point (pH 1.6). The dynamic parameters of pepsin macromolecules in solutions containing various metal ions, including potassium, cobalt, lead, cesium, and rubidium are studied. It is shown that the addition of these ions causes a decrease of the translational diffusion coefficients. It is found that an increase in temperature leads to the structural transition of a pure solution of pepsin in water. The activation energy of this transition is calculated using the Arrhenius law.