Retention of native-like structure in an acyclic counterpart of a β-sheet antibiotic

An acyclic derivative of the cyclic peptide antibiotic, ramoplanin, has been prepared. In aqueous solution, two-dimensional NMR spectroscopy indicates that the acyclic form adopts a threshold population of conformers in which at least part of the β-sheet characteristic of the intact ramoplanin persists. Thus, despite losing the entropic benefit which the macrocycle must lend to β-sheet formation, the polypeptide chain of the acyclic ramoplanin appears to display an innate tendency to adopt a native-like conformation.