page_title: List of biophysically important macromolecular crystal structures
section_title: Papain
hierarchical_section_title: List of biophysically important macromolecular crystal structures / Papain
caption_attribution_description: English: Potato carboxypeptidase inhibitor protein: at top is the C-terminal end that binds in the carboxypeptidase active site and would normally be the first enzymatic substrate in progressive cleavage of the polypeptide chain. However, the inhibitor C-terminus is SS-linked to the helix through a tight ring of SS bonds, so that the enzyme cannot suck in the next residue for cleavage. Alpha helix is in red, beta strands in blue, and SS bonds in yellow. Ribbon diagram hand drawn and colored by Jane Richardson between 1982 and 1984, from PDB file 4CPA.
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: 1968 - Papain
caption: CPA inhibitor
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