ABSTRACT
Structural biology was born over 50 years ago with the revelation of the structures of both deoxyribonucleic acid (DNA) and myoglobin (Mb) in full atomic detail. The structures of DNA and Mb provided evidence for a stark contrast between the structures of nucleic acids and proteins. On the one hand, the simple and elegant structure of DNA clearly illustrated a key structural determinant of nucleic acid structure, the hydrogen-bonding base-pairing network that provides both stability and specificity to the DNA structure. On the other hand, the structure of Mb exposed the inherent complexity of protein structure that is based on a combination of hydrogen bonding, hydrophobic, electrostatic, and metal ligand interactions. The structure of Mb foreshadowed what has now crystallized into one of the largest unsolved problems in science: the protein-folding problem, or the question of how the fundamental chemical structure of a polypeptide chain determines its protein structure, and therefore its biological activity (Dill et al. 2008).
