Tag Archives: actin

Calix[4]arene C-99 inhibits myosin ATPase activity and changes the organization of contractile filaments of myometrium

R. D. Labyntseva1, A. A. Bevza1, A. О. Lul’ko1, S. О. Cherenok2,
V. I. Kalchenko2, S. О. Kosterin1

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

Calix[4]arenes are cup-like macrocyclic (polyphenolic) compounds, they are regarded as promising molecular “platforms” for the design of new physiologically active compounds. We have earlier found that сalix[4]arenе C-99 inhibits the ATPase activity of actomyosin and myosin subfragment-1 of pig uterus іn vitro. The aim of this study was to investigate the interaction of calix[4]arene C-99 with myosin from rat uterine myocytes. It was found that the ATPase activity of myosin prepared from pre-incubated with 100 mM of calix[4]arene C-99 myocytes was almost 50% lower than in control. Additionally, we have revealed the effect of calix[4]arene C-99 on the subcellular distribution of actin and myosin in uterus myocytes by the method of confocal microscopy. This effect can be caused by reorganization of the structure of the contractile smooth muscle cell proteins due to their interaction with calix[4]arene. The obtained results demonstrate the ability of calix[4]arene C-99 to penetrate into the uterus muscle cells and affect not only the myosin ATPase activity, but also the structure of the actin and myosin filaments in the myometrial cells. Demonstrated ability of calix[4]arene C-99 can be used for development of new pharmacological agents for efficient normalization of myometrial contractile hyperfunction.

Study of the sites of plasminogen molecule which are responsible for inhibitory effect of Lys-plasminogen on platelet aggregation

Y. M. Roka-Moya, D. D. Zhernossekov, E. I. Yusova,
L. G. Kapustianenko, T. V. Grinenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: chemikdd@mail.ru

Plasminogen/plasmin system is involved in such important processes as thrombosis, inflammation and cancer. Plasmin and plasminogen mediate their action through plasminogen-binding proteins on the cell surface. Lys-plasminogen, but not Glu-plasminogen, shows inhibitory effect on platelet aggregation induced by ADP, collagen and thrombin in preparations of both: platelet-rich plasma and washed platelets. We have shown that the kringle domains of Lys-plasminogen mediate interaction of this proenzyme with platelet-surface proteins. The aim of the work is to study the role of certain kringle domains in the inhibitory effect of Lys-plasminogen and to determine possible plasminogen-binding proteins on the platelet surface. All studied plasminogen fragments (K1-3, K4 and K5) abolished the inhibitory effect of Lys-plasminogen on platelet aggregation. We observed that K5 was more effective than K1-3 and K4. Biotin-labeled Lys-plasminogen, Glu-plasminogen and plasminogen fragment K1-3 possessed the highest affinity for actin, whereas the binding of biotin-labeled mini-plasminogen and K4 to actin was negligible. We have suggested that inhibitory effect of Lys-plasminogen is due to the interaction of kringle domains of this proenzyme with membrane-bound proteins which are exposed on the platelet surface during activation and are involved in thrombus formation.