ISSN:
1573-8388
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary 1. By means of physical methods (IR and NMR spectra, ORD curves, dipole moments) and a theoretical conformational analysis, a study has been made of the conformational states of three topochemical analogs of valinomycin: cyclo-(D-Val-D-HyIv-L-Val-L-Lac)3 (II), cyclo-(D-HyIv-L-Ala-L-HyIv-D-Val)3 (III), and cyclo-(D-HyIv-D-Val-L-HyIv-L-Ala)3 (IV). 2. In compounds (II) and (III) steric interactions prevent the formation of “bracelet” conformations and the formation of complexes with alkali-metal ions. 3. In nonpolar media, compound (IV) assumes a “bracelet” conformation similar to that of valinomycin. 4. In view of steric hindrance, compound (IV) is incapable of adopting the “propeller” conformation that is characteristic for valinomycin, which leads to a reduced surface activity. 5. The conformation of the depsipeptide chain of the K+ complex of compound (IV) is similar to the conformation of the K+ complex of valinomycin. However, in it the cation is more feebly shielded from interaction with the solvent, which explains the higher stability and surface activity of the complex.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00563352
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