Premium
A study of the conformations of valinomycin in solution phase
Author(s) -
Wang Feng,
Zhao Chunxia,
Polavarapu Prasad L.
Publication year - 2004
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20103
Subject(s) - valinomycin , chemistry , density functional theory , computational chemistry , solvent effects , absorption spectroscopy , ab initio , solvent , crystallography , organic chemistry , potassium , physics , quantum mechanics
Vibrational absorption and vibrational circular dichroism (VCD) spectra of valinomycin are measured, in different solvents, in the ester and amide carbonyl stretching regions. The influence of cations, namely Li + , Na + , K + , and Cs + , in methanol‐ d 4 solvent is also investigated. Ab initio quantum mechanical calculations using density functional theory and 6–31G* basis set are used to predict the absorption and VCD spectra. A bracelet‐type structure for valinomycin that reproduces the experimental absorption and VCD spectra in inert solvents is identified. For the structure of valinomycin in polar solvents, a propeller‐type structure was optimized, but further investigations are required to confirm this structure. A symmetric octahedral environment for the ester carbonyl groups in the valinomycin–K + complex is supported by the experimental VCD spectra. The results obtained in the present study demonstrate that even for large macrocyclic peptides, such as valinomycin, VCD can be used as an independent structural tool for the study of conformations in solution. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004