'''The structure of the orthorhombic form of soft-shelled turtle lysozyme at 1.9 angstroms resolution'''
===The structure of the orthorhombic form of soft-shelled turtle lysozyme at 1.9 angstroms resolution===
==Overview==
The crystal structures of pheasant and guinea fowl lysozymes have been determined by X-ray diffraction methods. Guinea fowl lysozyme crystallizes in space group P6(1)22 with cell dimensions a = 89.2 A and c = 61.7 A. The structure was refined to a final crystallographic R-factor of 17.0% for 8,854 observed reflections in the resolution range 6-1.9 A. Crystals of pheasant lysozyme are tetragonal, space group P4(3)2(1)2, with a = 98.9 A, c = 69.3 A and 2 molecules in the asymmetric unit. The final R-factor is 17.8% to 2.1 A resolution. The RMS deviation from ideality is 0.010 A for bond lengths and 2.5 degrees for bond angles in both models. Three amino acid positions beneath the active site are occupied by Thr 40, Ile 55, and Ser 91 in hen, pheasant, and other avian lysozymes, and by Ser 40, Val 55, and Thr 91 in guinea fowl and American quail lysozymes. In spite of their internal location, the structural changes associated with these substitutions are small. The pheasant enzyme has an additional N-terminal glycine residue, probably resulting from an evolutionary shift in the site of cleavage of prelysozyme. In the 3-dimensional structure, this amino acid partially fills a cleft on the surface of the molecule, close to the C alpha atom of Gly 41 and absent in lysozymes from other species (which have a large side-chain residue at position 41: Gln, His, Arg, or Lys). The overall structures are similar to those of other c-type lysozymes, with the largest deviations occurring in surface loops. Comparison of the unliganded and antibody-bound models of pheasant lysozyme suggests that surface complementarity of contacting surfaces in the antigen-antibody complex is the result of local, small rearrangements in the epitope. Structural evidence based upon this and other complexes supports the notion that antigenic variation in c-type lysozymes is primarily the result of amino acid substitutions, not of gross structural changes.
==About this Structure==
==About this Structure==
2GV0 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Pelodiscus_sinensis Pelodiscus sinensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GV0 OCA].
2GV0 is a 1 chain structure of sequence from [http://en.wikipedia.org/wiki/Pelodiscus_sinensis Pelodiscus sinensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GV0 OCA].
==Reference==
==Reference==
Crystal structures of pheasant and guinea fowl egg-white lysozymes., Lescar J, Souchon H, Alzari PM, Protein Sci. 1994 May;3(5):788-98. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8061608 8061608]
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Revision as of 06:14, 17 February 2009
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The structure of the orthorhombic form of soft-shelled turtle lysozyme at 1.9 angstroms resolutionThe structure of the orthorhombic form of soft-shelled turtle lysozyme at 1.9 angstroms resolution
About this StructureAbout this Structure
2GV0 is a 1 chain structure of sequence from Pelodiscus sinensis. Full crystallographic information is available from OCA.
