[Effect of eosin Y on Mg2+-dependent ATPase activity of the myometrium actomyosin].
The effect of the reversible inhibitor of membrane-bound Ca2+ -transporting system in smooth muscle--eosin Y--on apparent kinetic parameters that characterize the sensitivity to Mg2+ of myometrium actomyosine ATPase reaction was investigated. It is shown that eosin Y decreases an affinity of actomyosin for Mg2+ and does not influence the number of turns of the smooth muscle actomyosin ATPase activity that was defined by Mg2+. This suggests possible competition of eosin Y with Mg2+ for the active center of actomyosin ATPase. However, the negatively charged inhibitor cannot be adsorbed on Mg2+-binding site of the active center because of essential differences in size, form and charge between eosin Y and Mg2+. Most likely, eosin Y acts on uterus smooth muscle actomyosin as an allosteric inhibitor. Consequently, the mechanism of eosin Y action on ATPase activity of myometrium contractile proteins is different from the mechanism of its influence on ATP-hydrolase enzyme systems of plasmatic membranes.
Labyntseva
R D
RD
Kosterin
S O
SO
D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D004801:Eosine Yellowish-(YS) / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D013552:Swine
D000205:Actomyosin; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins; D008274:Magnesium; D004801:Eosine Yellowish-(YS)