Structural Features of Azurin at 2.7 Å Resolution

Abstract

Abstract The phases for the x‐ray data for crystals of azurin from P. aeruginosa have been refined and extended from 3 Å to 2.7 Å resolution by a method based on the direct space averaging of the electron density of the four molecules in the asymmetric unit. The electron density in the present map is much improved over the earlier one, and most of the side‐chains are now evident. In the detailed fitting of a model to the present map, an alternative interpretation, conforming to the plastocyanin model and reversing the chain directions in strands one and two of the original azurin model, was found to better represent certain features of the present map. The surface of the molecule closest to the copper consists of an extended region of invariant or semiconserved hydrophobic residues. There is not a region of conserved charge that is not paired with a compensating charge.