In situ iodination and X-ray crystal structure of a foldamer helix bundle.

We report here the efficient in situ iodination of tyrosine-type side-chains located within a foldamer helix bundle, permitting structure determination using single-wavelength anomalous diffraction (SAD) methods. We suggest that this simple method may be of use to those engaged in structural foldamer research as a potential solution to the phase problem.