Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 7/1989)
The cover illustration shows the structure of the ascorbate oxidase from zucchini. It belongs to the group of blue oxidases and is the very first oxidase whose structure could be elucidated. Its more than 500 amino acid residues are folded into three domains, shown here as ribbons in violet, green-yellow, and blue. A type-l-copper (Cu5), which is reduced by the substrate, and a novel trinuclear complex, which contains eight histidine ligands and serves as an oxygen-binding and electron storage site, act as redox centers. The isolated Cub atom has no functional significance. The redox centers and the electron pathway are located inside the protein and are far removed from bulk water. Further details on the structural basis of light energy and electron transfer in biology are reported on by R. Huber in his Nobel lecture on page 848.