[The effect of calmodulin inhibitors and the new cardiotonic drug DPI 201-106 on the formation of interprotein bonds in the cardiac troponin complex].
Using the binding of labeled [125I]troponin C (TnC) to troponin I (TnI) and troponin (TnT) immobilized on a polyvinylchloride matrix, the Ca-dependent formation of interprotein bonds in the cardiac troponin complex and the effects of various drugs on the above reaction were studied. It has been found that in the absence of Ca2+ the dissociation constant, Kd, for the TnC-TnI complex in equal to (2.5 +/- 1.03).10(-7) M. In the presence of Ca2+ the number of binding sites increases twofold; the Kd value for the bonds formed thereby is (1.74 +/- 0.18).10(-7) M. The complex is stable to the effect of 5 M urea. TnC binding to immobilized TnT is nonspecific and is completely abolished by an addition of 5 M urea. DPI 201-106 used at concentrations up to 10(-3) M does not affect the Ca-dependent binding of TnC to TnI; trifluoperazine inhibits this interaction by 60%, whereas substance 48/80 inhibits the reaction by 50% when used at a concentration of 210 micrograms/ml. It is supposed that the compounds interacting with TnC affect, primarily, the cation-binding properties of troponin. These compounds can also inhibit the formation of interprotein bonds but only when used at much higher concentrations.
Feoktistov
I A
IA
Krylatov
A V
AV
Larionov
N P
NP
D000818:Animals; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002417:Cattle; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000737:chemistry*; D010879:Piperazines / Q000494:pharmacology*; D014336:Troponin / Q000737:chemistry* / Q000187:drug effects; D019209:Troponin C
D002147:Calmodulin; D010879:Piperazines; D014336:Troponin; D019209:Troponin C; C046261:DPI 201-106
Vliianie ingibitorov kal'modulina i novogo kardiotonicheskogo preparata DPI 201-106 na obrazovanie mezhbelkovykhh sviazeĭ v troponinovom komplekse serdtsa.