My talk will start out with brief remarks on the history of protein crystallography and on recent fascinating developments in methods of structural biology and continue with our studies since 1970 on proteolytic enzymes and their control. Proteolytic enzymes catalyse a very simple chemical reaction, the hydrolytic cleavage of a peptide bond. Nevertheless, they constitute a most diverse and numerous lineage of proteins. The reason lies in their role as components of many regulatory physiological cascades in all organisms. To serve this purpose and to avoid unwanted destructive action, proteolytic activity must be strictly controlled. The regulatory principles unveiled by structural studies offer new opportunities for therapeutic purposes as illustrated with examples from my laboratory with a focus on the essential intracellular protease, the proteasome in cancer and autoimmune disorders. I then will let you share my experience with the foundation and development of two biotech companies with different business models, but both based on basic academic research in structural biology.