[Effects of Ca2+-ATPase substrates on the kinetic properties of SH-groups from the sarcoplasmic reticulum].
The effects of ATP, GTP, ITP, UTP, CTP, AcP, pNPP and ADP on the kinetic properties of SH-groups of Ca2+-ATPase from sarcoplasmic reticulum were studied. Among the substrates used only ATP and ADP changed the reactivity of SH-groups of the enzyme; the effects of Ca2+ and  Mg2+ in this process were investigated. Inactivation of Ca2+-ATPase by NBD-chloride was performed. In the presence of high concentrations of ATP and ADP the enzyme inactivation was correlated with modification of fast SH-groups. Two different values of apparent Kd found for the interaction of ATP and ADP with the enzyme suggest that SR preparations contain two types of substrate binding sites. The data obtained are discussed within the framework of a scheme according to which Ca2+-ATPase functions in SR membranes as an oligomeric complex.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D007700:Kinetics; D008433:Mathematics; D012265:Ribonucleotides / Q000494:pharmacology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D012265:Ribonucleotides; D013438:Sulfhydryl Compounds; D000252:Calcium-Transporting ATPases
Vliianie substratov Ca2+-ATPazy na kineticheskie svoĭstva SH-grupp sarkoplazmaticheskogo retikuluma.