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The effect of some chemical modifying agents of the sarcolemma surface--dicyclohexicarbodiimide, trinitrobenzolsulphuric acid, dithiotreitol and nitrit-anions on passive transsarcolemmic accumulation of Ca2+ by the pig myometrium sarcolemma property oriented vesicules was studied. The comparative analysis of these substances action under proton transmembrane gradient dispersion is presented. The significance of surface amino-, carboxy groups and disulphide membrane bounds in Ca2+ transport mechanisms as a corresponding aspect to some contemporary ideas about Ca(2+)-channel has been defined. The hypothesis is made that the proton transmembrane gradient dissipation leads to dislocation of carboxyl groups and disulphid bounds in relation to the membrane surface resulting in increasing Ca(2+)-permeability of the sarcolemma. The increase of sarcolemma permeability for Ca2+ under the action of 10 nM NO-2 was demonstrated. On the base of experimental data the supposition was made that NO-2 modified amino- and carboxylate groups of the sarcolemma surface. Under the chemical modification of these groups the nitrit-anions inhibit transsarcolemmic Ca2+ movement. NO-2 is not a result of sarcolemma surface SH-groups oxidation, while possibly NO2- protects some functionally important disulphide bridges of Ca(2+)-channel from their chemical restoration.

Chymotryptic (Ch-Cl) and Mg(2+)-papain subfragments 1 of (Mg-Cl) skeletal myosin has been studied. Mg-Cl is known to differ from Ch-Cl by the presence of the regulatory light chain (RLC) and elongated heavy chain including C-end hinge segment. Experimental data prove the decisive part of coordination bondings with bivalent cations in stabilization of RLV on myosin head hinge segment. Hydrophobic interactions are also significant that is evidenced by the intensive aggregation between subfragment Mg-Cl molecules, after RLC dissociation.

Cytoplasmic and mitochondrial molecular forms of glutamine synthetase (CE 6.3.1.2) have been isolated from the carp muscle with purification degree of 100 and 165 times and output 9.0%. It is established that the temperature optimum of the cytoplasmic form activity is 30 degrees C and that of mitochondrial one--20 degrees C; the pH optimum for the both molecular forms is 6.0 and 8.2. The optimal ratio [Me2+] : [ATP] for the isolated form is 2:1; Km (seeming) of the cytoplasmic form in the presence of Mg2+ is 6.0 mM for glutamate, 0.035 for ammonium, for ATP 0.5 and 0.7 for magnesium ions; these values for the mitochondrial form are: 14.3, 0.048, 1.0 and 0.8 mM, respectively. Activity of the both glutamine synthetases with Mg2+ ions is almost by 50% higher than that of glutamine synthetases with Mn2+ ions. Seasonal regularities of the synthesis of molecular glutamine synthetase forms have been established in vivo. Cytoplasmic form is present in the muscles all year round, while mitochondrial one only in winter at low temperature of the environment and fish starvation. Differences in properties and seasonal character of synthesis of molecular glutamine synthetase forms in carp muscles are a result of diversity of their functional role.