Crystallization of proton channel peptides

Crystals have been grown of two similar peptides that form ion‐conducting channels in diphytanoyl phosphatidylcholine bilayers. These crystals were grown by slow evaporation of the organic solvent, 2,2,2‐trifluoroethanol. Crystals of one of the peptides have been characterized by X‐ray diffraction, and X‐ray data have been measured to 2.3 Å resolution. Earlier it was proposed that the ion‐conducting channels formed by these peptides consist of four peptides associated as a parallel α‐helical tetramer. On the basis of the space group and unit cell dimensions of the crystals, a packing scheme for the peptide is proposed that is consistent with a tetrameric channel.