1cc3

From Proteopedia

Revision as of 07:34, 3 February 2008

PURPLE CUA CENTER

Overview

The X-ray structure of an engineered purple CuA center in azurin from, Pseudomonas aeruginosa has been determined and refined at 1.65 A, resolution. Two independent purple CuA azurin molecules are in the, asymmetric unit of a new P21 crystal, and they have nearly identical, conformations (rmsd of 0.27 A for backbone atoms). The purple CuA azurin, was produced by the loop-engineering strategy, and the resulting overall, structure is unperturbed. The insertion of a slightly larger Cu-binding, loop into azurin causes the two structural domains of azurin to move away, from each other. The high-resolution structure reveals the detailed, environment of the delocalized mixed-valence [Cu(1.5).Cu(1.5)] binuclear, purple CuA center, which serves as a useful reference model for other, native proteins, and provides a firm basis for understanding results from, spectroscopic and functional studies of this class of copper center in, biology. The two independent Cu-Cu distances of 2.42 and 2.35 A (with, respective concomitant adjustments of ligand-Cu distances) are consistent, with that (2.39 A) obtained from X-ray absorption spectroscopy with the, same molecule, and are among the shortest Cu-Cu bonds observed to date in, proteins or inorganic complexes. A comparison of the purple CuA azurin, structure with those of other CuA centers reveals an important, relationship between the angular position of the two His imidazole rings, with respect to the Cu2S2(Cys) core plane and the distance between the Cu, and the axial ligand. This relationship strongly suggests that the fine, structural variation of different CuA centers can be correlated with the, angular positions of the two histidine rings because, from these, positions, one can predict the relative axial ligand interactions, which, are responsible for modulating the Cu-Cu distance and the electron, transfer properties of the CuA centers.

About this Structure

1CC3 is a Single protein structure of sequence from Pseudomonas aeruginosa with as ligand. Known structural/functional Sites: and . Full crystallographic information is available from OCA.

Reference

Structural basis of electron transfer modulation in the purple CuA center., Robinson H, Ang MC, Gao YG, Hay MT, Lu Y, Wang AH, Biochemistry. 1999 May 4;38(18):5677-83. PMID:10231517

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