Detection of a pH-dependent conformational change in azurin by time- resolved phosphorescence

Citations of this article
Mendeley users who have this article in their library.


Azurin, a blue copper protein from the bacterial species Pseudomonas aeruginosa, contains a single tryptophan residue. Previous fluorescence measurements indicate that this residue is highly constrained and unusually inaccessible to water. In the apoprotein this residue also possesses a long- lived room-temperature phosphorescence (RTP), the nonexponential decay of which can be resolved into two major components associated with lifetimes of 417 and 592 ms, which likely originate from at least two conformations of the protein. The relative weights of these two decay components change with pH in good correlation with a change in protonation of His-35, which has been studied in Cu(II) azurin. Interestingly, the structural changes characterized in earlier work have little effect on the fluorescence decay and appear to occur away from the tryptophan residue. However, in the present work, the two RTP lifetimes suggest conformations with different structural rigidities in the vicinity of the tryptophan residue. The active conformation that predominates below a pH of 5.6 has the shorter lifetime and is less rigid. Phosphorescence decays of several metal derivatives of azurin were also measured and revealed strong similarities to that of apoazurin, indicating that the structural constraints upon the metal-binding site are imposed predominately by the protein.




Hansen, J. E., Steel, D. G., & Gafni, A. (1996). Detection of a pH-dependent conformational change in azurin by time- resolved phosphorescence. Biophysical Journal, 71(4), 2138–2143.

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free