PMC

Copper site of A. denitrificans Met121His azurin. (A) High pH form. The indicated distances are the mean values over the subunits in HP1 and HP2. (B) Low pH form. The displayed distances are the mean values between subunits C and D of LP. Image produced with setor ().

Polypeptide stretch of A. denitrificans Met121His azurin that undergoes the conformational change on protonation of His121 at low pH (3.5). (A) High pH form. The indicated distances are mean values between subunits A and B of both HP and LP. (B) Low pH form. The displayed distances are the mean values between subunits C and D of LP. Image produced with setor ().

Overlay of the low pH form (subunit D of LP, blue) onto high pH form (subunit A of LP, green) of the copper sites and the polypeptide stretch 120–124. The included 2.45-Å resolution F_o–F_c omit electron density map was calculated with residues 120–123, and nitrate in subunits D was removed and running a 200-cycle positional refinement before map calculation. The map has been contoured at 3.0 σ. Image produced with setor ().