Synthetic Ionophores Research Articles

13C‐Kernresonanzspektroskopische und elektromotorische Untersuchungen der Wechselwirkung von neutralen Carriern mit Ionen in Membranen

Investigation of the interaction of neutral carriers with ions in membranes by 13C‐NMR. and EMF.‐measurements.Applying a simple model, information on the interaction of neutral carriers with cations as well as on the ion pair formation may be obtained through 13C‐NMR. and potentiometric studies of PVC‐supported ion selective liquidmembranes in contact with aqueous solutions. The results indicate that carriers for K+ (nonactin) and synthetic ionophores for Ca2+ show an association of the carrier‐complexes with lipophilic anions. The extent of complex formation of the carrier in the presence of lipophilic anions in the sample solution is in agreement with earlier interpretations of the anion interference of cation selective liquid‐membrane electrodes.

Active transport of glutamine and glutamic acid in membrane vesicles from Mycobacterium phlei

Summary In addition to proline, the active transport of glutamine and glutamate was demonstrated in the electron transport particles from Mycobacterium phlei . The uptake of glutamine and glutamic acid proceeded against the concentration gradient with various substrates and was sensitive to respiratory inhibitors and synthetic ionophores. The mode of energy transduction for the uptake of glutamine and glutamate appears to differ from that of proline, since the latter requires Na + although respiration per se is a prerequisite for the uptake of all the three amino acids. Studies with competitive inhibitors suggest that the carrier protein or binding site(s) for glutamine and glutamate are different from that of proline. The transport of proline, glutamine and glutamate occurs in the absence of latent ATPase, arsenate and in the absence of a proton gradient.