4hz1

Publication Abstract from PubMed

The apoprotein of Pseudomonas aeruginosa azurin binds iron(II) to give a 1:1 complex, which has been characterized by electronic absorption, Mossbauer, and NMR spectroscopies, as well as X-ray crystallography and quantum-chemical computations. Despite potential competition by water and other coordinating residues, iron(II) binds tightly to the low-coordinate site. The iron(II) complex does not react with chemical redox agents to undergo oxidation or reduction. Spectroscopically calibrated quantum-chemical computations show that the complex has high-spin iron(II) in a pseudotetrahedral coordination environment, which features interactions with side chains of two histidines and a cysteine as well as the C horizontal lineO of Gly45. In the (5)A(1) ground state, the d(z(2)) orbital is doubly occupied. Mutation of Met121 to Ala leaves the metal site in a similar environment but creates a pocket for reversible binding of small anions to the iron(II) center. Specifically, azide forms a high-spin iron(II) complex and cyanide forms a low-spin iron(II) complex.

Azurin as a Protein Scaffold for a Low-coordinate Nonheme Iron Site with a Small-molecule Binding Pocket.,McLaughlin MP, Retegan M, Bill E, Payne TM, Shafaat HS, Pena S, Sudhamsu J, Ensign AA, Crane BR, Neese F, Holland PL J Am Chem Soc. 2012 Dec 5;134(48):19746-57. doi: 10.1021/ja308346b. Epub 2012 Nov, 20. PMID:23167247^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.