ABSTRACT
The ability of the aliphatic polyamines to inhibit [figure: see text] the ATPase activity of smooth muscle actomyosine satisfies the succession: spermine > spermidine > putrescine that is correlated with magnitude of positive charge at physiological value of pH. The most effective inhibitor of the ATP hydrolysis process is the spermine, which highest inhibitory action is manifested at 10(-3) M concentration, in lesser concentration (10(-5) M) activates the actomyosine ATPase. While defining the kinetic parameters of the ATP hydrolysis reaction catalyzed by uterus myometrium the correlation between inhibiting the ATPase activity of myometrium contractile complex under introduction into the incubation medium of 10(-3) M spermine and decreasing the affinity of actomyosine for ATP was made; the activating effect of spermine on ATPase activity of actomyosine complex in the presence of 10(-5) M spermine correlated with the increase of actomyosine affinity for Mg2+.
Subject(s)
Adenosine Triphosphatases/metabolism , Biogenic Polyamines/pharmacology , Muscle, Smooth/drug effects , Myometrium/drug effects , Myosins/metabolism , Animals , Female , Muscle, Smooth/enzymology , Muscle, Smooth/metabolism , Myometrium/enzymology , Myometrium/metabolism , Putrescine/pharmacology , Spermidine/pharmacology , Spermine/pharmacology , SwineABSTRACT
In order of estimating some regularities of ethanol effective action on the uterus smooth muscles contractile proteins the effects of spiritus introduced into incubation medium on myometrium actomyosine ATP-hydrolase activity and superprecipitation was studied. ATP-hydrolase activity was displayed as more sensitive to ethanol action; its dependence on ethyl spiritus concentration had three-phase character expressed in two inhibiting and one activating sites. While defining the kinetic parameters of ATP hydrolysis reaction catalysed by uterus myometrium the correlation between inhibition the ATP-hydrolase activity of myometrium contractile complex under introducing into incubation medium 2% ethanol and decreasing the affinity of actomyosine to Mg2+ was made; the highest activating effect of ethanol on ATP-hydrolase activity of actomyosine complex in the presence of 8% ethanol correlated with increasing the affinity of actomyosine to Mg2+ and ATP.
Subject(s)
Actomyosin/metabolism , Adenosine Triphosphate/metabolism , Ethanol/pharmacology , Hydrolases/metabolism , Myometrium/drug effects , Animals , Female , Hydrolysis , Kinetics , Myometrium/enzymology , Myometrium/metabolism , SwineABSTRACT
The inhibiting effect of Pb2+, Zn2+ and Cd2+ on Mg(2+)-dependent superprecipitation and ATPase activity of myometrium actomyosin. The inhibiting effect of heavy metals cations on the both processes satisfies the succession: Pb2+ > Zn2+ > Cd2+. Cadmium and zinc ions in concentration of 1 mM stimulate the initial velocity (v0) of Mg(2+)-dependent superprecipitation by 25% and 80%, respectively, while the lead ions under the same concentration inhibit the initial velocity by 40%. It is possible that these results evidence for the direct effect of ions of heavy metals on active-myosin interaction (tested by v0). May be that the mechanisms of Cd2+ and Zn2+ action on the one hand and Pb2+, on the other hand, on the interaction of the contractile proteins of the uterus smooth muscle are different. Cations of Pb, Cd or Zn introduced to the incubation medium instead of Mg2+ (5 mM) also stimulate both superprecipitation and ATPase activity but the level of the both processes decreases by 65%, 20% and 5%, respectively, as compared to control (i.e. in presence of Mg2+). It is probable that the cadmium, zinc and lead cations can substitute magnesium ions in the active centre of myosine as well as in the sections of significance for the process of superprecipitation of actomyosine. At the same time the substitution is less efficient for realization of the superprecipitation reaction and ATP-hydrolase process than when magnesium ions are available in the incubation medium. EDTA and EGTA do not remove the inhibiting effect of Pb2+, Cd2+ and Zn2+ on the contractile activity and ATP-hydrolase reaction of actomyosine complex of the uterus smooth muscle. The results obtained prove that the ions of heavy metals can effect the uterus smooth muscles at the stage of actin-myosine interaction.
Subject(s)
Metals, Heavy/pharmacology , Muscle, Smooth/drug effects , Myosins/metabolism , Uterus/drug effects , Adenosine Triphosphate/metabolism , Animals , Catalysis , Chemical Precipitation , Female , Ions , Muscle, Smooth/enzymology , Muscle, Smooth/metabolism , Swine , Uterus/enzymology , Uterus/metabolismABSTRACT
Kinetic regularities of the reaction of superprecipitation of myometrium actomyosin, as well as the effect of different concentrations of EGTA, EDTA and diphosphonic acids on this process have been studied. Results obtained are of interest from the viewpoint of possible practical use of diphosphonates as factors modifying interaction of the contractile proteins of the uterus smooth muscles under the pathology of contractile response.
Subject(s)
Actomyosin/drug effects , Calcium , Chelating Agents/pharmacology , Myometrium/drug effects , Actomyosin/chemistry , Animals , Cations, Divalent , Chemical Precipitation , Edetic Acid , Egtazic Acid , Female , Magnesium , Organophosphonates , Swine , Uterine Contraction/drug effectsABSTRACT
A method is developed to isolate lysyl-tRNA-synthetase from 93-95%-purity postribosomal supernatant fraction of skeletal muscle homogenate in rabbit. Novelty of the method is the ATP usage for muscle homogenization, which permits shortening the number of operations during the enzyme isolation. The molecular weight of protein is 68 +/- 10 kDa, the monomer unit consists of 540 amino acids and contains a carbohydrate component.
