STM of isolated complexes of R-Phycoerythrin: direct observation of the γ-subunit at the centre of the complex

Scanning tunnelling microscopy was used to study the topography of single complexes of the photosynthetic protein R-Phycoerythrin and to determine the location of the γ-subunit. This study has resolved an ambiguity in the positioning of the γ-subunit from X-ray crystal structure analysis which arose from the symmetry-related averaging of the X-ray diffraction pattern which led to a loss of resolution.