page_title: List of biophysically important macromolecular crystal structures
section_title: Ribonuclease
hierarchical_section_title: List of biophysically important macromolecular crystal structures / Ribonuclease
caption_attribution_description: English: Elastase (Ser protease) ribbon diagram, hand-drawn from PDB file 1EST.
context_page_description: Crystal structures of protein and nucleic acid molecules and their complexes are central to the practice of most parts of biophysics, and have shaped much of what we understand scientifically at the atomic-detail level of biology. Their importance is underlined by the United Nations declaring 2014 as the International Year of Crystallography, as the 100th anniversary of Max von Laue's 1914 Nobel prize for discovering the diffraction of X-rays by crystals. This chronological list of biophysically notable protein and nucleic acid structures is loosely based on a review in the Biophysical Journal. The list includes all the first dozen distinct structures, those that broke new ground in subject or method, and those that became model systems for work in future biophysical areas of research.
context_section_description: 1967 - Ribonuclease A (PDB file 2RSA) is an RNA-cleaving enzyme stabilized by 4 disulfide bonds.  It was used in Anfinsen's seminal research on protein folding which led to the concept that a protein's 3-dimensional structure was determined by its amino-acid sequence. Ribonuclease S, the cleaved, two-component form studied by Fred Richards, was also enzymatically active, had a nearly identical crystal structure (PDB file 1RNS), and was shown to be catalytically active even in the crystal, helping dispel doubts about the relevance of protein crystal structures to biological function.
caption: Two domains of elastase
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