Extracellular pH modulates kinetics of the Na(+),K(+)-ATPase.

To investigate effects of pH on the Na(+),K(+)-ATPase, we used the Xenopus oocytes to measure transient charge movements in the absence of extracellular K(+), and steady-state currents mediated by the pump as well as ATPase activity. The activity of purified Na(+), K(+)-ATPase strongly depends on pH, which has been attributed to protonation of intracellular sites. The steady-state current reflects pump activity, the transient charge movement voltage-dependent interaction of external Na(+) ions with the pump molecule and/or conformational changes during Na(+)/Na(+) exchange.

Phosphorylation of the alpha-subunits of the Na+/K+-ATPase from mammalian kidneys and Xenopus oocytes by cGMP-dependent protein kinase results in stimulation of ATPase activity.

Phosphorylation of Na+/K+-ATPase by cGMP-dependent protein kinase (PKG) has been studied in enzymes purified from pig, dog, sheep and rat kidneys, and in Xenopus oocytes. PKG phosphorylates the alpha-subunits of all animal species investigated. Phosphorylation of the beta-subunit was not observed.

Spectroscopic, biological, and antitumor studies on N-ethyl- and N-propylimidazole platinum(II) complexes.

Platinum(II) halide complexes with N-ethylimidazole (N-EtIm) and N-propylimidazole (N-PropIm) of the Pt(L)2X2 and Pt(L)4X2 types (X = Cl, Br, I) were prepared and characterized by far infrared spectra, electronic spectra, and conductivity measurements. The inhibitorial activity of some complexes on the Ca,Mg-dependent ATPase and the antitumor studies of the Pt(L)4Cl2 derivatives have been investigated. Pt complexes are not inhibitory active in comparison to the same Pd complexes (if c = 10(-4) M).