| Atomic views of protein structures are determined with increasing pace in the last twenty years by a rapid development of methods and instrumentation of protein crystallography, electron microscopy, and nuclear magnetic resonance, allowing the determination of very large and complex protein structures. These structures document the beauty and unlimited versatility of the proteins´ architecture, but reveal also unexpected relationships, allowing views on biological evolution far back in time. The structures are a basis for understanding the proteins’ binding specificities and catalytic properties (chemistry), their spectral and electron transfer properties (physics), and their roles in physiological systems (biology and medicine). They allow design and development of specific ligands of target proteins opening novel strategies for therapeutic intervention and development of new medicaments and for plant protection. |