Azurin

Each monomer of an azurin tetramer has a molecular weight of approximately 14kDa, contains a single copper atom, is intensively blue, and has a fluorescence emission band centered at 308 nm.

[4] Considerable experimental evidence exists to suggest that hydrogen bonds play a role in the long-distance electron transfer mechanism of azurin.

[4] Azurin is a monomeric protein that weighs approximately 14 kDa and is composed of 128 amino acids forming eight beta-strands arranged in a beta-barrel formation.

Notable structural features elucidated by crystallography include the beta-sandwich motif formed from eight interlocking beta strands,[5] as well as an alpha-helical segment outside the barrel linking beta-sheets 4 and 5.

[8] When expressed in nitrogen-fixing organisms, azurin serves as the electron donor to nitrite reductase, an enzyme in the denitrification pathway of the nitrogen cycle.

A phase I clinical trial in the United States demonstrated both partial and complete tumor regression effects in fifteen stage IV cancer patients treated with the p28 amino-acid fragment of azurin.

[13] Another phase I trial with the p28 fragment demonstrated azurin’s therapeutic effects against pediatric patients with brain tumors; subsequently, the USFDA approved the designation of p28 as an orphan drug for glioma.

A Pymol rendering of the copper binding domain of 3fqy showing a copper atom surrounded by four associating ligands.
The copper binding domain of azurin rendered in PyMol, with four of the five copper-binding ligands labeled. The distance (in angstroms) from the copper atom to each individual ligand has been recorded.