Low-resolution electron-density and anomalous-scattering-density maps of Chromatium high-potential iron protein

Abstract

Electron-density and Bijvoet-difference Fourier (anomalous-scattering-density) maps, at a resolution of 4 A, have been calculated for the Chromatium high-potential iron protein. Phases were obtained from two heavy-atom isomorphous derivatives, PtCl2−6 and UO2F3−5. The most prominent peak in the electron density map coincides with the most prominent peak in the Bijvoet-difference Fourier map, and there are no other coincidences of minor peaks in the two maps. It is concluded that the four iron atoms of Chromatium high-potential iron protein reside in a single unresolved cluster.