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Total proteins extractable from a number of rat tissues were partitioned in the aqueous Ficoll-400-Dextran-70 biphasic system. The partition coefficient of the total proteins extractable from a given tissue, K, was shown to be a tissue-specific constant. The free energy of transfer of a CH2 group from water to the aqueous solution of a given protein extract, delta(delta gCH2), was calculated from the corresponding K-value using the correlation relationship between K and delta(delta gCH2) reported earlier. It is suggested to use the parameter delta(delta gCH2)-value as a measure of the relative hydrophobic character of biological fluids and tissues. The difference between the delta(delta gCH2)-values for blood plasma medium and for a given tissue medium is used to quantify the difference in the relative hydrophobic character of the biological tissues and fluids under study. The possibilities to use the above characteristics in drug research are considered.

The effect of salts KSCN, KI, KBr, KCI, KC104, KF, K2SO4 and NH4CI, LiC1, NaC1, KC1, CsC1 on the binodials of the phase diagrams for aqueous biphasic dextranpolyvinylpyrrolidone, dextran-polyvinyl alcohol, dextran-ficoll and dextran-polyethylene glycol systems was studied. It is established that the K-salts present at the concentrations of 0.1 and 0.5 mol/kg alter the binodials of the phase diagrams for the above systems. The effect of a salt is found to be related to the lyotropy of the salt quantified by the salt molal surface tension increment. It is assumed that phase separation in an aqueous polymer biphasic system is affected by the presence of a salt mainly due to the effect of the salt on the structure and/or state of water in the system.

Concentration effects of KSCN, KC104, KI, KBr, KNO3, KC1, KF and K2SO 4 on the compatibility of dextran with ficoll, polyvinylpyrrolidone and poly(ethylene glycol) at fixed polymer concentration ratios were studied in aqueous solution. The results obtained are considered in terms of the Patterson theory of Az-effecc It is assumed that phase separation in an aqueous solution of two nonionic polymers results from the appearance of two different water structures in the vicinity of the phase polymers. The data obtained are considered in terms of the concept of "salting-in-salting-out" effects of neutral salts on aqueous solubility ofbiopolymers. The salt effects observed are attributed to two antagonistic influences of salts on the electrostatic (dipole-dipole) polymer-water interactions and on the water-water interactions in the vicinity of the phase polymers.