Plasma gamma-globulin fraction proteins, copper and zinc cations, and metal-modified gamma-globulins induce the production of IFN by human leukocytes. Binding of zinc cations attenuates the realization of the IFN-inducing effects of human serum gamma-globulin, while binding of copper cations potentiated this effect. Activity of IFN and the dynamics of its production correspond to those in response to phytohemagglutinin stimulation. The pool of induced IFN contains acid-labile (up to 60%) and acid-stable (up to 40%) constituents. Anti-IFN-alpha antibodies do not modify activity of produced IFN. The results indicate the possibility of gamma-globulin conformation allowing stimulation or attenuation of the protein capacity to induce the production of IFN pool with predominant content of IFN-gamma.

Interactions of human serum gamma-globulin with zinc cations in solution were studied by differential spectrophotometry in UV light. Supraphysiological concentrations of zinc caused an increment in optical density of protein solution reflecting the effect of gamma-globulin saturation with the metal. Zinc concentrations below physiological led to hypochromism in the protein absorption spectrum. Conformation changes in gamma-globulin during interactions with zinc are analyzed for the surface and intramolecular binding sites and are compared with the effects of copper cations.

No abstract

No abstract

Magnetic properties of multilayers, consisting of nanogranular (Co40Fe40B20)50(SiO2)50 layers as thin as magnetic granule diameter alternating the α-Si:H or SiO2 layers and the single layer film (Co40Fe40B20)50(SiO2)50 with the thickness much larger than the magnetic granule diameter are reported and compared. The thick single layer film is ferromagnetic but the multilayer film with the ultrathin granular layers and SiO2 spacer is superparamagnetic. This is interpreted as the result of increasing percolation threshold in the 2D granular media above 50% concentration of magnetic granules in the multilayer with the nonmagnetic and dielectric SiO2 spacer. The multilayer with the α-Si:H spacer is superparamagnetic at 300 K but it becomes ferromagnetic, when temperature is below 250 K. It is assumed to be resulted from the exchange interaction of magnetic granules through the semiconductor α-Si:H layers. The value of exchange interaction through the semiconductor spacer is estimated.

No abstract

No abstract

Binding of zinc cations to human serum gamma-globulin was studied by molecular ultrafiltration. The content of free metal in the filtrate was evaluated by reaction with o-phenanthroline. Conformation characteristics of the protein were determined by UV spectrophotometry. Our findings suggest that gamma-globulin molecule contains several zinc binding sites differing by corresponding constants and successively occupied with increase in the content of bound metal. The parameters of zinc binding correspond to those obtained in experiments with copper. Conformation status of protein with bound zinc differs significantly from that of protein with bound copper cations.