K.V. Fedorova, M.A. Gurova, Zhang Xiaolei, G.P. Petrova, Moscow State University, Russia
Metals play an important role in a human organism. Concentrations of metals, particularly, heavy metals, exceeding the maximum allowable level in the organism are dangerous for persons. At present, it is of topical interest to study molecular mechanisms of the effect of heavy metal ions on enzymes, and to develop sufficiently simple and reliable physical methods for environmental monitoring of the occurrence of heavy metals in natural environments.
An effective method for studying macromolecule solutions is Rayleigh light scattering [1, 2]. The known Debye equation helps relate the experimentally measured quantity-the light scattering coefficient (or turbidity) of a solution-to the solution concentration and the intermolecular interaction coefficient (the second virial coefficient in expansion of osmotic pressure in terms of low concentrations). The equation permits determination of the mass M of scattering particles and the intermolecular interaction parameter B.
Dynamic light scattering as well as static is connected with fluctuations of dispersing particle concentration. The concentration dependencies of transmitting diffusion coefficient and scattering parameter are determined by the same virial coefficient, namely the connection between dynamic parameter (Dt), static molecular parameters (B, M) and static viscosity (h) determined by equation:
The results of our experiments has shown that charged macromolecules dynamic properties and radii of formed scattering particles in solutions essentially depend on net charge condition of enzymes and can be used for diagnostics and control.
For macromolecules solutions it is possible to connect a normalized autocorrelation function of light scattering intensity with a translation diffusion coefficient:
g^(1)(t) = exp^(-Dtq^2tau)
The function g(1)(t) can be determined by a method of optical mixing of light (correlation spectroscopy).
In our study, scattering properties of water enzyme solutions were investigated by the automatical set-up element and a scattered radiation photoelectron detector.
In this work was studied the effect of ions some metals (K+, Na+, Pb2+, Fe3+, Eu3+) on enzymes (pepsin, collagenase, lyzosume, creatine kinase) in water solutions.
The nature of interaction enzyme macromolecules in case when the solution contains metal ions with a large ionic radius depends largely on dipole-dipole forces. Enzyme molecules may come extremely closely to one another to form a macromolecular complex-a dipole cluster
The mass and radius of enzyme clusters forming in the solution increases by more than one order of magnitude as compared to the mass of a macromolecule and reaches its maximum near the isoelectric point of enzyme. This effect explains an organism poisoning with heavy metals.
Ksenya Vyacheslavovna Fedorova
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