Abstract in Deutsch

The first part of the thesis describes the x-ray structure analysis of the proprotein convertase furin. Before the phase problem could be solved by multiwavelength anomalous dispersion (MAD), a crystal transformation and a special measuring strategy were required because of a high mosaicity and a large unit cell. Finally, it was possible to solve the crystal structure of furin, which gives insight into the high substrate specificity of proprotein convertases. Two calcium binding sites could be determed by diffraction experiments near the absorption edge of calcium. Based on the crystal structure of furin other proprotein convertases were build by homology modelling. In the second part, the crystal structure of the non-collagenous domain NC1 of collagen IV is presented, which was solved by MAD experiments. Collagen IV is a major component of basement membranes and has a novel covalent side-chain cross-link between of methionine and lysine.