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International audience; Phosphorus is an abundant element in living organisms. It is traceable by its X-ray absorption spectrum which shows a strong white line at its K-edge, comparable with that observed for the L(III) edges of rare earth ions. With purple membrane, the variation of the imaginary part of the anomalous dispersion of phosphorus is found to be close to 20 anomalous electron units. Anomalous diffraction experiments at wavelengths near the K-absorption edge of phosphorus confirm this result. The spatial distribution of lipids derived from anomalous diffraction agrees with earlier results from neutron diffraction. Test experiments on single crystals of the carrier protein using 5.76 A photons gave a first low-resolution diffraction pattern. Various techniques of crystal mounting were attempted. In addition, fluorescence measurements on a solution of threonine synthase appear to hint at a change of the phosphate environment of the cofactor upon activator binding.

The wiggler beamline BW6 at DORIS has been optimized for de-novo solution of protein structures on the basis of MAD phasing. Facilities for automatic data collection, rapid data transfer and storage, and online processing have been developed which provide adequate conditions for high-throughput applications, e.g., in structural genomics.

The high‐flux beamline at the ESRF will be one of the first beamlines and will be available to users at the start of ESRF operation in 1994. It will provide a highly monochromatic photon flux with very low divergence through a small sample. The brilliance of the photon beam will be much higher than at existing sources. The optics is optimized for ultrasmall angle x‐ray scattering experiments and biological macromolecular crystallography at 12 keV. This corresponds to a wavelength of about 0.1 nm. An undulator with a period of 46 mm and a maximum deflection parameter K of 2.08 has been chosen as an insertion device. The optics will consist of a cryogenically cooled Si(111) double monochromator followed by a double focusing mirror. In this paper the planned setup of the beamline is described. The optical properties have been studied with the ray‐tracing program shadow.