The structure of oxy-erythrocruorin at 1.4 Å resolution

Abstract Stable oxy-erythrocruorin crystals were prepared from the met form and diffraction intensities recorded by a novel procedure applying a hydrogen sulphide/oxygen gas mixture in a flow cell. The crystal structure was analysed by difference Fourier methods and partly refined at 1.4 A resolution. The dioxygen was found to be bound end-on and hydrogen-bonded to a water molecule. The iron, which is 0.17 A out of the haem plane in the deoxy form (Steigemann & Weber, manuscript in preparation), changes its position only very slightly and moves to the proximal side. Further conformational changes are minimal and far smaller than observed for the carbonmonoxy and cyano derivatives (Steigemann & Weber, manuscript in preparation).