1rro
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REFINEMENT OF RECOMBINANT ONCOMODULIN AT 1.30 ANGSTROMS RESOLUTION
OverviewOverview
A refinement of the oncomodulin crystal structure at 1.30 A resolution has, been carried out with X-ray data from the recombinant protein. The, crystallographic R-factor values are 0.169 for 19,995 reflections in the, range 6.0 to 1.30 A, which were used for the restrained least-squares, refinement, and 0.176 for 20,186 observed reflections in the range 10.0 to, 1.30 A. This high resolution refinement has enabled us to make more, definitive statements about the molecular structure than was possible, heretofore. The present model includes residues 1 to 108, the two Ca2+ of, the CD and EF loops, two intermolecular Ca2+, and 103 water molecules per, oncomodulin molecule. The electron density maps indicate disordered, orientations for ten residues on the hydrophilic surface of the molecule., The pattern of molecular aggregation via intermolecular Ca2+, which occurs, in the native rat oncomodulin structure, is also present in the, recombinant oncomodulin structure. The Cys18 side-chain is not in a, position that would be easily accessible for molecular dimerization via a, disulphide bond. The substitution of Glu59, which is preserved in all the, determined species of parvalbumin, by Asp59 in oncomodulin seems to break, a stabilizing hydrogen bond in the CD loop and render the main-chain in, positions 59 to 60 somewhat unstable. This instability in the CD loop, and, the strong tendency of oncomodulin for molecular aggregation via, intermolecular Ca2+, appear to be the two outstanding features that may, account for oncomodulin's biological peculiarities.
About this StructureAbout this Structure
1RRO is a Single protein structure of sequence from Rattus norvegicus with CA as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Refinement of recombinant oncomodulin at 1.30 A resolution., Ahmed FR, Rose DR, Evans SV, Pippy ME, To R, J Mol Biol. 1993 Apr 20;230(4):1216-24. PMID:8487302
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