1erd: Difference between revisions

[[Image:1erd.gif|left|200px]]<br /><applet load="1erd" size="350" color="white" frame="true" align="right" spinBox="true"  

The NMR structure of the pheromone Er-2 from the ciliated protozoan Euplotes raikovi has been determined in aqueous solution. The structure of this 40-residue protein was calculated with the distance geometry program DIANA from 621 distance constraints and 89 dihedral angle constraints; the program OPAL was employed for the energy minimization. For a group of 20 conformers used to characterize the solution structure, the average pairwise RMS deviation from the mean structure calculated for the backbone heavy atoms N, C alpha, and C' of residues 3-37 was 0.31 A. The molecular architecture is dominated by an up-down-up bundle of 3 short helices of residues 5-11, 14-20, and 23-33, which is similar to the structures of the homologous pheromones Er-1 and Er-10. Novel structural features include a well-defined N-cap on the first helix, a 1-residue deletion in the second helix resulting in the formation of a 3(10)-helix rather than an alpha-helix as found in Er-1 and Er-10, and the simultaneous presence of 2 different conformations for the C-terminal tetrapeptide segment, i.e., a major conformation with the Leu 39-Pro 40 peptide bond in the trans form and a minor conformation with this peptide bond in the cis form.

1ERD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Euplotes_raikovi Euplotes raikovi]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ERD OCA].  

[[Category: Bradshaw, R A.]]

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