M. V. Lomonosov Moscow State University Faculty of Physics Charles University in Prague Faculty of Mathematics and Physics INTERACTIONS BETWEEN BIOMARKERS and MAIN BLOOD PROTEINS Gibizova V. V. , Petrova G. P. , Sergeeva I. A. , Fedorova K. V. E-mail: gibizova@physics. msu. ru Nowadays biophysics investigations are developing and are important for medicine applications. PHOTON CORRELATION SPECTROSCOPY Static Light Scattering Average scattering intensity is a function of the (particle) molecular weight and the 2 nd virial coefficient. M – Molecular weight, R 90 – Rayleigh ratio c – Concentration, H – Optical constant B – 2 nd Virial coefficient, NA – Avogadros number, ν 0 – excluded Volume, i. e. volume of the molecule which supersedes all other 2 nd virial coefficient is a thermodynamic property. describing the interaction strength between the molecule and the solvent. For samples where B>0, the molecules tend to stay in solution (protein molecules prefer contact with buffer). When B=0, the molecule-solvent interaction strength is equivalent to the molecule-molecule interaction strength – the solvent is described as being a theta solvent (protein doesn’t mind buffer). When B<0, the molecule will tend to fall out of solution or aggregate (protein doesn’t like buffer). RESULTS INVESTIGATED OBJECTS Gadopentetic acid C 14 H 20 Gd. N 3 O 10 Paramagnetic contrast agents for MRI: 1) for enhancing of picture contrast; 2) for the detection of tumors, including small and bad visualized. gamma-globulin globular protein, determines the immune properties of the body. The investigated water solution: bovine gamma-globulin; bovine gammaglobulin+gadopentetic acid PHOTOCOR COMPLEX Parameters of laser: wavelength - 647 nm, power P=25 m. W The conditions of experiment: temperature of investigated solutions T=20ºC, p. H~7, 0 CONCLUSIONS Our results show that the slope of the straight is positive for the pure solution of gamma-globulin, but the addition of gadopentetic acid changes the sigh of 2 nd virial coefficient of intermolecular interaction (positive slope becomes negative).