Mechanism of inhibition of the calcium pump of sarcoplasmic reticulum by thapsigargin.

摘要: The steady-state ATPase activity of sarcoplasmic-reticulum (Ca(2+)-Mg2+)-ATPase is inhibited by thapsigargin at a molar ratio 1:1, with dissociation constant for estimated to be in the sub-nanomolar range. In presence thapsigargin, only single Ca2+ ion binds ATPase. Similarly, addition incubated results release one two originally bound ions. As monitored fluorescence nitrobenzo-2-oxa-1,3-diazole-labelled ATPase, appears shift transition between E1 and E2 conformations towards E2. Addition prevents phosphorylation P(i) very low level ATP, as observed previously nonylphenol.