Wilhelm Stürmer

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Experiments were designed to characterize several partial reactions of the Na,K-ATPase and to demonstrate that a model can be defined that reproduces most of the transport features of the pump with a single set of kientic parameters. We used the fluorescence label 5-iodoacetamidofluorescein, which is thought to be sensitive to conformational changes, and(More)
In the first part of the paper, evidence has been presented that electrochromic styryl dyes, such as RH 421, incorporate into Na, K-ATPase membranes isolated from mammalian kidney and respond to changes of local electric field strength. In this second part of the paper, fluorescence studies with RH-421-labeled membranes are described, which were carried out(More)
The electrogenic properties of the Na,K-ATPase were studied by correlating transient electrical events in the pump molecule with conformational transitions elicited by an ATP-concentration jump. Flat membrane fragments containing a high density (∼8000 μm−2) of oriented Na,K-ATPase molecules were bound to a planar lipid bilayer acting as a capacitive(More)
A fluorescent dye, RH421, has been used to characterize charge movements associated with cation and cardiotonic steroid binding to Na,K-ATPase and to a specifically trypsinized preparation, so-called "19-kDa membranes." A fluorescence decrease induced by Na+ is attributed to electrogenic binding of one Na+ ion from the cytoplasm. The apparent affinity for(More)
Membrane fragments containing a high density of Na, K-ATPase can be noncovalently labeled with amphiphilic styryl dyes (e.g., RH 421). Phosphorylation of the Na,K-ATPase by ATP in the presence of Na+ and in the absence of K+ leads to a large increase of the fluorescence of RH 421 (up to 100%). In this paper evidence is presented that the styryl dye mainly(More)
Recently we have presented evidence that the fluorescence probe RH 421 can be used to detect binding and release of ions at the extracellular face of the pump since these processes are associated with translocation of electrical charge. Applying this method to experiments with cardiac glycosides we found that: (1) ouabain induced fluorescence changes of the(More)
Intramolecular dynamics in Na,K-ATPase molecules have been studied by ultraviolet fluorescence spectroscopic methods: determination of temperature-dependent shifts in steady-state spectra, site-selective red-edge effects and their temperature dependence, and time-resolved emission decay as a function of excitation and emission wavelengths. The combination(More)
telien Wert ~ = o,oo6 findet man mit ~ # = ~ ~ m aus (2) 2 m fl = 0,47, d. h. v ~ IO la sec-1. Dies ist die riehtige Gr6t3enordnung der Molekelfrequenz in LSsung~). 2. Die Gasmolekeln sind in der Flfissigkeit fiberwiegend ionisiert. --. Die Ionen kSnnen dureh Hinzutreten yon geladenen Teilehen entstehen (Beispiel: NH + aus NHa) oder dureh Abspaltung(More)
One radiograph of Hunsrück slate shows the presence of a drop-shaped "worm". This image resembles an acoel platyhelminth in the presence of an apparently eversible pharyngeal structure, but no trace can be tound of the complex reproductive structures of platyhelminths, making full identification impossible. Another more elongate worm-like image shows the(More)