Franziska Hempelmann

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The proteorhodopsin (PR) family found in bacteria near the ocean's surface consists of hundreds of PR variants color-tuned to their environment. PR contains a highly conserved single histidine at position 75, which is not found in most other retinal proteins. Using (13)C and (15)N MAS NMR, we were able to prove for green PR that His75 forms a pH-dependent(More)
Partition coefficients (P) of 48 cardenolides were determined in octanol/water. Furthermore Rm-values of most of these substances were measured in different thin-layer chromatography systems (TLC) and related to P. Regression analysis revealed that the best linear fit of the data was obtained when Rm-values from reversed-phase TLC on octanol impregnated(More)
The saluretic agent xipamide (4-chloro-5-sulfamoyl-2',6'-salicyloxylidide; Aquaphor) is a lipophilic substance as demonstrated by solubilities and partition coefficients. In the physiological pH-range, however, xipamide forms an anion which has an octanol-water partition coefficient of approx. 1. Two steps of ionization were investigated photometrically.(More)
Nachdem lange Zeit die Morphologie und besonders die Biologie der Naididen zugunsten systematischer ErSrterungen im Hintergrund stehen mul~te, hat man sich erfreulicherweise in den letzten Jahren wieder etwas eingehender den mit dem bei dieser Oligoeh~ttenfamilie auftretenden Fortpflanzungsweehsel im Zusammenhang stehenden eigentfimlichen(More)
The inhibition of carbonic anhydrase by xipamide (4-chloro-5-sulfamoyl-2',6'-salicyloxylidide, Aquaphor), a poorly watersoluble saluretic agent, is determined with the Philpot method in the presence of 5 per cent N,N-dimethyl-formamide. The addition of the amide does not affect the enzyme. For xipamide 1.1 times 10-5 M is found as the 50 per cent(More)
Intestinal absorption of 15 cardenolides has been examined in cats. The 3H-labelled substances were injected intraluminally into ligated duodenal loops of anaesthetized animals. 3H-Concentrations were followed in the portal circulation and in the bile. 1 h after drug administration the duodenal sac was removed, and the residual in the lumen then was washed(More)
The diuretic and saluretic effectiveness of xipamide (4-chloro-5-sulfamoyl-2',6'-salicyloxylidide, Aquaphor) is determined and compared to those of chlortalidone and furosemid in normal subjects. The substance is revealed as a potent diuretic agent. In the range of 0.035--0.750 mg/kg body weight the dose-response curve of orally administered xipamide for(More)
By equilibrium dialysis the binding of 19 cardenolides and cardenolide conjugates to human plasma proteins has been measured. The binding constants were compared with octanol-water partition coefficients described previously. No correlation was found between the two properties. Glycosides and conjugates of a certain genine show the same extent of protein(More)
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