Experiment 1: S-SAD of cubic insulin

In this experiment, cubic crystals of bovine insulin are used for experimental phase determination using diffraction data collected at a wavelength of λ = 1.77 Å. This so-called Sulphur-SAD (S-SAD) approach has in the recent years gained quite some popularity. To date, approximately 100 structures have been solved by S-SAD. The elegance of structure determination based on anomalous signal of light atoms such as S is that it is based on native proteins, i.e. no heavy atom derivatives are required. In order to enhance the rather small anomalous signal of S, data collection is performed at a slightly longer wavelength.