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Published November 10, 1998 | public
Journal Article

High-potential states of blue and purple copper proteins

Abstract

Electrochemical measurements show that there are high-potential states of two copper proteins, Pseudomonas aeruginosa azurin and Thermus thermophilus Cu_A domain; these perturbed states are formed in guanidine hydrochloride (GuHCl) solution in which the proteins are still blue (azurin) and purple (Cu_A). In each case, the high-potential state forms reversibly. Absorption (azurin, Cu_A), visible circular dichroism (azurin, Cu_A), resonance-Raman (Cu_A), and EPR (Cu_A) spectra indicate that the structure of the oxidized copper site of each high-potential form is very similar to that of the native protein. It is proposed that GuHCl perturbs one or more H-bonds in the blue or purple copper active site, thereby allowing Cu(I) to adopt a more favorable coordination structure than that in the rigid cavity of the native protein.

Additional Information

© 1998 Elsevier Science B.V. Received 27 April 1998, Revised 30 July 1998, Accepted 19 August 1998, Available online 20 April 1999. P.W.-S. thanks the Swedish Technical Research Council for a postdoctoral fellowship. This investigation was supported by NSF, NIH, the Arnold and Mabel Beckman Foundation, the Nobel Committee for Chemistry (B.G.M.), the Swedish Natural Science Research Council (B.G.K.), and the Research Corporation (Cottrell Science Award to M.G.H.).

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023