Tag Archives: plasma membrane

Mathematical modeling of calcium homeostasis in smooth muscle cells while activity of plasma membrane calcium pump is modulated

S. O. Karakhim, V. F. Gorchev, P. F. Zhuk, S. O. Kosterin

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: laserlab@biochem.kiev.ua;  kinet@biochem.kiev.ua

A mathematical model of intracellular calcium homeostasis in smooth muscle cells has been investigated by computer modelling method. The results of calculations showed that for the plasma membrane calcium pump (PMCA) the limiting rate (VmPM) increasing or the Michaelis constant (KmPM) decreasing result in a lowering of the Ca2+ concentration in cytosol and sarcoplasmic reticulum (SR); the slight VmPM decreasing or KmPM increasing result in fluent cytosolic Ca2+ strengthening due to slow basal influx (SBI) since a massive release of Ca2+ from SR does not occur. The further VmPM decreasing or KmPM increasing stimulate the Ca2+-induced Ca2+ release from SR and the system passes into oscillation mode; when the certain low VmPM or high KmPM level is reached the oscillations of Ca2+ concentration in cytosol are stopped, there is only first oscillation after which a new level of cytosolic Ca2+ concentration is formed fluently: this level is higher than in the initial basal condition (IBC). Sensitivity of myocytes with the lowering­ of VmPM or increasing KmPM to agonist action is rising but sensitivity of myocytes with increasing VmPM or decreasing KmPM to agonist action is reducing. If the PMCA parameters (VmPM or KmPM) are changed then passive influx of Ca2+ in cytosol from extracellular space remains virtually invariable and it is equal to SBI value during the whole process. Initial rate of PMCA in a new equilibrium condition (NEC) is equal virtually to initial rate in IBC: it allows to calculate a new value VmPM or KmPM  from cytosolic Ca2+ concentration in NEC.

Kinetic regularities of calixarene C-90 action on the myometrial plasma membrane Ca(2+),Mg(2+)-ATPase activity and on the Ca(2+) concentration in unexcited сells of the myometrium

T. O. Veklich1, A. A. Shkrabak1, Yu. Yu. Mazur1, R. V. Rodik2,
V. I. Boyko2, V. I. Kalchenko2, S. O. Kosterin1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: kinet@biochem.kiev.ua; vik@ioch.kiev.ua

Plasma membrane Ca2+,Mg2+-ATPase is an important element of general myometrium tonus control mechanism, which also makes a contribution to muscle tension relaxation after its contraction. Expiriments were done on the myometrial cell plasma membrane suspension, which was treated with 0.1% digitonin solution. The authors have investigated the inhibitory action of calix[4]arene C-90 (5,11,17,23-tetra(trifluor)methyl(phenylsulphonylimino)-methylamino-25,26,27,28-tetra propoxi-calix[4]arene) on the Ca2+,Mg2+-ATPase activity (the magnitude of І0.5 was 20.2 ± 0.5 mkM). The inhibitory action of calix[4]arene C-90 on the activity of Ca2+,Mg2+-ATPase is explained as cooperative action of four trifluormethyl(phenylsulfonylimino)methylamino groups that are spatially oriented on the calix[4]-arene base rather than with the action of tetraphenol macrocycle or separate pharmacophore sulphonilamidin groups. Conside­ring established kinetic pattern of calix[4]arene C-90 inhibitory action on the plasma membrane Ca2+,Mg2+-ATPase­ activity, stationary kinetical model of basal calcium concentration control in unexcited uterus myocytes was develo­ped. It is assumed that obtained results may be promising for creation of new generation (“supramolecular”) pharmacological agent – uterus basal tonus stimulator – on the base of calix[4]arene C-90.

The сalix[4]arene C-107 is highly effective supramolecular inhibitor of the Na+,K+-АТРase of plasmatic membrane

O. V. Bevza1, T. O. Veklich1, O. A. Shkrabak1, R. V. Rodik2, V. I. Kalchenko2, S. O. Kosterin1

 1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: kinet@biochem.kiev.ua;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: vik@bpci.kiev.ua

The inhibition of the Na+,K+-АТРase activity of the myometrium cell plasma membranes with calixarene С-107 (5,17-diamino(2-pyridyl)methylphosphono-11,23-di-tret-butyl-26,28-dihydroxy-25,27-dipropoxycalix[4]arene) was investigated. It has been shown that calixarene С-107 reduced the Na+,K+-АТРase activity more efficiently than ouabain did, while it did not practically influence the “basal” Mg2+-АТРase activity of the same membrane. The magnitude of the cofficient of inhibition I0.5 was 33 ± 4 nМ, Hill coefficient was 0.38 ± 0.06. The model calixa­rene C-150 – the calixarene “scaffold” (26,28-dihydroxy-25,27-dipropoxycalix[4]arene), and the model compound М-3 (4-hydroxyaniline(2-pyridine)methylphosphonic acid) – a fragment of the calixarene С-107, had practically no influence on the enzymatic activity of Na+,K+-АТРase and Mg2+-АТРаse.  We carried out the computer simulation of interaction of calixarenes C-107 and the mentioned model compound with ligand binding sites of the Na+,K+-АТРase of plasma membrane and structure foundation of their intermolecular interaction was found out. The participation of hydrogen, hydrophobic, electrostatic and π-π (stacking) interaction between calixarene and enzyme aminoacid residues, some of which are located near the active center of Na+,K+-АТРase, was discussed.

Effect of adaptogenic preparations on Na(+)/H(+)-antiporter function in plasma membrane of corn root cells under salinity conditions

N. O. Kovalenko, Zh. I. Bilyk, T. A. Palladina

Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Kyiv;
e-mail: tatiana_palladina@ukr.net

Salinity is a hard stress factor for plant organisms which negative effect is caused chiefly by sodium toxic for plants. Plant cells try to remove Na+ from their cytoplasm outside and to vacuolar space by secondary active Na+/H+-antiporters. Their functions can be intensified by gene engineering methods­ however we try do it with the help of non-toxic bio­active preparations. A comparison of their effect on the plasma membrane of Na+/H+-antiporters was carried out on corn seedling roots of Zea mays L. exposed at 0.1 M NaCl. Before we have established that Methyure used by seed pretreating possesses a high salt protective ability as against Ivine. It was found that without NaCl exposition Na+/H+-antiporter­ activity in root plasma membrane was nearly unnoticeable but increased slightly with seedling age. Methyure and Ivine did not influence its activity in control root seedling. One day 0.1 M NaCl exposition evoked a considerable increasing of Na+/H+-antiporter activity and its gene expression but these effects disappeared at 10 day NaCl exposition. Methyure use reinforced Na+/H+-antiporter activity and prolonged it at NaCl exposition without effect on its gene expression whereas Ivine effects on these indexes were insignificant. Obtained results showed that the salt protective capability of Methyure is connected with plasma membrane Na+/H+-antiporter activation which is realized on molecular level.

Kinetics of inhibitory effect of calix[4]arene С-90 on activity of transporting plasma membrane Cа(2+),Mg(2+)-ATPase of smooth muscle cells

T. O. Veklich1, A. A. Shkrabak1, Yu. Yu. Mazur1,
R. V. Rodik2, V. I. Kalchenko2, S. O. Kosterin1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: kinet@biochem.kiev.ua; vik@ioch.kiev.ua

In experiments on the suspension of myometrium cell plasma membrane, processed by 0.1% digitonin, the inhibitory action of calix[4]arene C-90 (5,11,17,23-tetra(threeftor)methyl(phenilsulphonilimino)-methylamino-25,26, 27,28-tetrapropoxy-calix[4]arene) on the activi­ty of Ca2+,Mg2+-ATPase was investigated. The authors also examined the influence of calix[4]arene in different concentration on affinity of enzyme (Ca2+,Mg2+-ATPase) for the ATP and ions of Mg and Ca, and its influence on cooperative effect and maximum velocity of ATP hydrolysis. It is shown that calix[4]arene does not influence the affinity of Ca2+,Mg2+-ATPase for the ATP, which means that these two compounds have different binding centers­. Also calix[4]arene has no influence on affinity and cooperative effect of Ca ions, if it is used in concentration lower than 50 µM. Calix[4]arene slightly increases coefficient of Ca2+,Mg2+-ATPase activation by magnesium chloride. In all three cases, where ATP, Mg and Ca ions are used to test the impact of calix[4]arene, maximum velocity of ATP hydrolysis significantly decreases. All these results clarify that calix[4]arene implements its inhibitory action through mechanism of uncompetitive inhibition of Ca2+,Mg2+-ATPase activity.

Mg(2+),ATP-dependent plasma membrane calcium pump of smooth muscle cells. ІІ. Regulation of activity

T. О. Veklich, Iu. Iu. Mazur, S. О. Kosterin

Palladin Institute of Biochemistry, National Academy of Science of Ukraine, Kyiv;
e-mail: veklich@biochem.kiev.ua,
yuliya.vorona@gmail.com

Plasma membrane Ca2+-pump is one of key proteins, which takes part in Ca2+ exchange in smooth muscle cells. It has a lot of diverse functions from control of basal cytoplasmal Ca2+ concentration to regulation of proteins  involved in Ca2+-dependent signal pathway. Ca2+ pump function is often depen­dent on the isoform or even form of alternative splicing. Allowing for a variety of Ca2+-pump functions and properties, which were reviewed in detail in the first part of our review article cycle (Ukr. Biochem. J., 2015; 87(1)), the precise control of the mentioned pump activity is very important for cell functioning­. The other part of this article is dedicated to different regulation factors of smooth muscle plasma membrane Ca2+-pump activity: endogenous and exo­genous, biotic and abiotic factors. Special attention is given to literature data and own results about design and the search of selective plasma membrane Ca2+-pump inhibitor which would allow examining its functioning in smooth muscle cells more meticulously.

Mg(2+),ATP-dependent plasma membrane calcium pump of smooth muscle cells. I. Structural organization and properties

T. O. Veklich, Iu. Iu. Mazur, S. O. Kosterin

Palladin Institue of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: veklich@biochem.kiev.ua; yuliya.vorona@gmail.com

Tight control of cytoplasm Ca2+ concentration is essential in cell functioning. Changing of Са2+ concentration is thorough in smooth muscle cells, because it determines relaxation/constraint process. One of key proteins which control Са2+ concentration in cytoplasm is Mg2+,ATP-dependent plasma membrane calcium pump. Thus, it is important to find compoumds which allowed one to change  Mg2+,ATP-dependent plasma membrane calcium pump activity, as long as this topic is of current interest in biochemical research which regards energy and pharmacomechanical coupling mechanism of muscle excitation and contraction. In this article we generalized literatute and own data about properties of smooth muscle cell plasma membrane Ca2+– pump. Stuctural oganization, kinetical properties and molecular biology are considered.