1a2w: Difference between revisions

The dimer of bovine pancreatic ribonuclease A (RNase A) discovered by, Crestfield, Stein, and Moore in 1962 has been crystallized and its, structure determined and refined to a 2.1-A resolution. The dimer is 3D, domain-swapped. The N-terminal helix (residues 1-15) of each subunit is, swapped into the major domain (residues 23-124) of the other subunit. The, dimer of bull seminal ribonuclease (BS-RNase) is also known to be, domain-swapped, but the relationship of the subunits within the two dimers, is strikingly different. In the RNase A dimer, the 3-stranded beta sheets, of the two subunits are hydrogen-bonded at their edges to form a, continuous 6-stranded sheet across the dimer interface; in the BS-RNase, dimer, it is instead the two helices that abut. Whereas the BS-RNase dimer, has 2-fold molecular symmetry, the two subunits of the RNase A dimer are, related by a rotation of approximately 160 degrees. Taken together, these, structures show that intersubunit adhesion comes mainly from the swapped, helical domain binding to the other subunit in the "closed interface" but, that the overall architecture of the domain-swapped oligomer depends on, the interactions in the second type of interface, the "open interface.", The RNase A dimer crystals take up the dye Congo Red, but the structure of, a Congo Red-stained crystal reveals no bound dye molecule. Dimer formation, is inhibited by excess amounts of the swapped helical domain. The possible, implications for amyloid formation are discussed.

1A2W is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with CL and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Structure known Active Site: AVE. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1A2W OCA].  

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