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Calix[4]arene C-97 (code is shown) is the macrocyclic compound which has lipophilic intramolecular higly-structured cavity formed by four aromatic cycles, one of which on the upper rim is modified by methylene bisphosphonic group. It was shown that calix[4]arene C-97 (100 microM) efficiently inhibits ATPase activity of myosin subfragment-1 from pig myometrium, the inhibition coefficient I(0.5) being 83 +/- 7 microM. At the same time, this compound at 100 microM concentration significantly increases the effective hydrodynamic diameter of myosin subfragment-1, that may be indicative of intermolecular complexation between the calix[4]arene and myosin head. Computer simulation methods (docking, molecular dynamics, involving the Grid) have been used to clarify structural basis of the intermolecular interaction of calix[4]arene C-97 with myosin subfragment-1 of the myometrium; participation of hydrophobic, electrostatic and pi-pi (stacking) interactions between calix[4]arene C-97 and amino acid residues of myosin subfragment-1, some of them being located near the active site of the ATPase has been found out.

A successive treatment with sodium iodide and digitonin of the myeline, microsome and synaptosome fractions of the cattle brain tissue resulted in obtaining the preparations of "soluble", Na+, K+-ATPase with a rather high specific activity non-containing practically Mg2+-dependent ATPase. To estimate the degree of these preparations structural heterogeneity they were subjected to analytical ultracentrifugation and disc-electrophoresis in polyacrylamide gel. The data obtained suggest an insignificant degree of heterogeneity for the "soluble" Na+, K+-ATP-ase preparations.

A comparative study was carried out of some properties of "soluble" Na+, K+-ATPase obtained from different subcellular membrane brain structures by means of non-ionic detergents of triton X-100 and digitonin. It is established that temperature and pH-optima of "soluble" Na+, K+-ATPase are close to these optima of the initial membrane preparations. A certain difference is observed in the dynamics of temperature and pH-dependence of Na+, K+-ATPase activity in the extracts from different subcellular structures. The stability of the preparations in storage was investigated. A conclusion is made that more stable enzyme extracts may be obtained by means of digitonin.

Mg2+-dependent Ca2+-activated ATPase (Mg2+, Ca2+-ATP-ase) of microsome fraction from grey matter of great cerebral hemispheres of cattle is activated by 0.1% solution of digitonin. Simultaneously 30-60% of initial fraction protein is extracted, respectively, with 0.1-0.3% concentrations of digitonin. The Mg2+- and Mg2+, Ca2+-ATPase activities manifest in solubilized protein. The maximal solubilization of both enzymes is reached when treating the fraction of brain microsomes with 0.3% solution of digitonin, the Mg2+, Ca2+-ATPase activity is not manifested in the 0.2% digitonin extract of this fraction. The Mg2+, Ca2+-ATPase activity is not always manifested in the 0.4% digitonin extract of the sediment which was obtained after extracting the initial fraction with 0.2% solution of digitonin. Addition of 0.2% extract to it causes manifestation or increase of the Mg2+, Ca2+-ATPase activity. Thus, minimum two components which are extracted by detergent in different concentrations or one of the extracted components which is an activator of solubilized Mg2+, Ca2+-ATPase may be necessary for manifestation of this activity in the solubilized components of the fraction of brain microsomes. The membrane components extracted with digitonin possess evidently a small molecular weight as they compose 7.5% polyacrylamide gel in which 0.4% digitonin extract of the brain microsome fraction is divided into 7-8 electrophoretic zones.