Pseudoazurin

Abstract

Pseudoazurin is a small blue copper protein isolated from denitrifying bacteria. Its amino acid sequence and molecular structure are distinct from plastocyanin, azurin, and other members of the cupredoxin family. The Type I Cu center responsible for the intense blue color has copper with 2 His, Cys, and Met ligands in a distorted tetrahedral array. Structures of oxidized and reduced forms of the protein show small, but significant differences. Pseudoazurin transfers electrons to and from nitrite reductase. Site‐directed mutagenesis and other techniques have shown that the likely interaction surface is the hydrophobic surface to which the copper atom is closest, surrounded by positively charged residues that interact with negatively charged counterparts on its electron transfer partners.

New molecular packing in a crystal of pseudoazurin fromAlcaligenes faecalis: a double-helical arrangement of blue copper

“…These were reported to be packed in a head-to-head manner. The head-to-head contact may not be favourable for the self-interaction of native PAzes because they have lysine residues which form a positively charged ring surrounding a hydrophobic head (Adman, 2006). Furthermore, negatively charged residues located at the other end of the protein can accelerate a head-to-tail or other types of interaction.…”

“…Pseudoazurin (PAz) is a blue copper protein which typically consists of eight -strands and two -helices (Adman, 2006). The blue copper site in PAz has a distorted tetrahedral geometry showing a highly anisotropic electron paramagnetic resonance spectrum, which is a mixture of axial and rhombic signals (Abdelhamid et al, 2007;Yamaguchi et al, 2016).…”