The Met121Glu azurin mutant has been crystallized and the structure determined at a resolution of 2.3 A. In the crystal structure a carboxyl oxygen of Met121Glu is coordinated to the metal at a distance of 2.2 A. Single-crystal resonance Raman spectroscopy was used to show that the glutamic acid residue in the copper site was in the protonated state. Titration of this residue gives rise to a number of unusual, pH-dependent properties: as the pH is increased from 4 to 8, the S(Cys)-Cu ligand-to-metal charge transfer bands are blue shifted and their intensity ratio is reversed, the EPR signal changes from type 1 copper to a new form of protein-bound copper, and the redox potential changes from 370 to 180 mV. The spectroscopic changes in this pH interval are consistent with a two-state model. From the pH dependence of the optical and EPR spectra, pKa = 5.0 for the glutamic acid in the oxidized protein was determined.

[reaction: see text] The Sakurai-Hosomi-type allylation of aromatic and heteroaromatic aldehydes can be catalyzed by the new heterobidenate bipyridine monoxide PINDOX with high enantioselectivities. The sterochemical outcome is mainly controlled by the axial chirality in PINDOX, which in turn is determined by the annulated terpene units.

The crystal structure of azurin mutant Phe114Ala from Pseudomonas aeruginosa has been solved by molecular replacement. The final crystallographic R value is 0.185 for 9832 reflections to a resolution of 2.6A. The root-mean-square deviation for main-chain atom positions is 0.020 A between the four independent monomers in the asymmetric unit. The mutant Ala114 crystallized from PEG 4000 in a new crystal form and the crystals are monoclinic, P21, a = 51.0, b = 83.6, c = 66.4A and fl = 110.5 ° . The four molecules in the asymmetric unit are packed as a dimer of dimers and are related by an approximate twofold axis. The dimer packing and the dimer contact region are very similar to that of the Alcaligenes denitrificans azurin dimer. The