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Choline Chloride; Adenosine Triphosphatase; Cation Binding; Fluorescence Emission Intensity; High affInity Binding Site
Abstract:
To link proposed features of the Na+/K+-ATPase reaction cycle to the molecular structure, spectroscopic studies mainly concerning the elucidation of partial reactions are carried out. This can be done by introducing fluorescence labels such as the F1TC-group (1) which enables the study of alkali ion binding as a key feature of this ion pump. According to earlier studies, a correlation between the fluorescence emission intensity and the position of the E1/E2 equilibrium is suggested: low fluorescence intensity in the presence of K+ has been attributed to E2, high intensity to E1(1–5). Evidence will be presented that this correlation concerning E1 is not fulfilled. Membrane-bound Na+/K+-ATPase has been prepared from pig kidney according to (6), the FITC-enzyme according to (1); details are given in (7).