NMR spin-echo study of the lyophilized biomass of Candida utilis yeasts at different growth stages]

Characteristics of the mobile water fraction isolated from some intracellular structures of freeze-dried cells of Candida utilis were studied as a function of the growth phase by the NMR spin-echo method. Part of the mobile water fraction in the log phase decreases down to ten percent of the biomass weight as compared with 2,5-4% in the stationary phase and in the beginning of the lag phases. Mobility of this water is invariable. A considerable decrease of the mobile water fraction is observed in the post-stationary phase too. A decrease of the mobile water fraction correlates with a decrease of the durability of C. utilis cells and is connected probably with some defects in the membrane structure of the cells and their incomplete development in the log phase of the growth.     

Polysaccharide biological activity dependent on structural characteristics]

Anti-Influenza and interferonogenic activity of polysaccharides from the glucane class produced extracellularly by the yeast-like organism Aureobasidium pollulans was studied on albino mice. The polysaccharides differed from each other by the branching level and content of bonds beta-C1-C3 and alpha-C1-C between the monomers. At the moment of the drugs administration to the albino mice the level of the early interferon was in correlation with the following 2 factors: the level of the polysaccharide branching and the percentage of bonds beta-C1-C3, while the amount of interferon produced in 24 hours correlated only with the percentage of bonds beta-C1-C4. The anti-influenza activity of the polysaccharides depended on the level of interferon production induced by them in the mice. Preparations stimulating production of sufficient amounts of both early and later interferon had the maximum activity.     

Interactions of neurotropic drugs with phosphatidylcholine bilayer. Effects on sorption of polyvalent cations]

It is found that neurotropic drugs, whose molecules have positively-charged amino groups and a considerable hydrophobic region (in size), can be incorporated into the phospholipid bilayers. This results in a decrease of the lifetime of Pr3+ cations in the membrane-associated state. No correlation was found to exist between local anaesthesia activity of the study drugs and its capability of displacement polyvalent cations from the membrane surface.     

Translation mobility of water isolated in the cells of lyophilized Cryptococcus albidus var. diffluens yeasts by the NMR impulse method

The method of NMR spin echo in a combination with the impulse gradient of the magnetic field was used to study the self-diffusion of water isolated in the cells of lyophylized Criptococcus. A relative fall of the amplitude of spin echo (factor R) in relation to the value of magnetic field impulse gradient (g), their duration (delta) and temporary distance between them (delta). The studies were carried out in the temperature range of 20 degrees divided by 80 degrees C. It has been shown that the fraction of isolated mobile water is located in intracellular permeable compartments with an average size of 0.6.10--4 cm at 20 degrees C. The coefficient of selfdiffusion of isolated water of Criptococcus (0.25.10--5 cm2S--1 at 20 degrees C) and the activation energy of selfdiffusion (4.4 ccal/mole at 20 degrees divided by 60 degrees C) were determined, permeability of walls of water-containing compartments taken into account.     

Broadening of the organ specificity of the action of polynucleotide interferon inducers]

Interferon titers in the blood and brain of mice and their protection from the herpes virus were compared after the animal exposure to poly(G).poly(C) duplex, both native and modified with cis-diammine dichloroplatinum (II). It was shown that the duplex platination especially at the level of the poly(G) strand resulted in sharp rising of the interferon titers in the extracts of the animal brain and rearrangement of the types of interferon induced in the brain to predominance of gamma-interferon. The interferonogenesis indices correlated with the duplex protective activity against the herpes virus. It was concluded that the platinum binding could increase the membrane specificity of the duplex and stimulate its penetration through the hematoencephalic barrier. Possible structural changes in the duplex under the action of platinum (II) resulting in the observed effect are discussed.     

The effect of low molecular weight ligands on relaxation of water protons in protein solutions

Interaction of low-molecular ligands (LML) isolated from blood serum albumin (SA) and serum proteins leads to higher T1 values for water protons compared with those observed in LML-free solutions, although the total amount of bound water increases. The latter was revealed by low-temperature NMR spectroscopy, as well as by the amount of water sorbed on SA + LML at a relative humidity P/Ps greater than 0.7. In the region 0.2 less than P/Ps less than 0.6 the amount of SA + LML-sorbed water decreased, as compared with that in SA indicating that the oppositely charged groups of LML screen some charged groups of the protein. A decrease of charge-to-charge interactions in solution, or with a high water content, leads to the hydration of those groups. The increase of the T1 value for water protons in solution is, probably, due to a hindered exchange between the sorbed water and bulk water. It is outlined that charge interactions between macromolecules may significantly affect water sorption by proteins.