Plastocyanin and the blue copper proteins

Abstract

This review is concerned with the properties of the type 1 blue copper proteins [1–4], a class of protein incorporating a single Cu atom and involved in redox processes. Within the class most information is available for plastocyanin, a component of photosynthetic electron transport, which has proved to be a particular focus of recent research. Relevant to the whole area of metalloprotein study is the more general question of how and over what distance electrons are transferred. Rapid, i.e. efficient, long-distance (> 10 A) electron transfer between metal centres is known to occur in biological systems, and attempts to better understand such processes is a subject of widespread current interest [7–14]. For reactions of two large biomolecules, specific relative orientations are required at the time of reaction, and questions relating to the docking process and association prior to electron transfer are highly relevant. For example, plastocyanin, which is a solute in the inner thylakoid of the chloroplast, is required to associate and electron transfer with its redox partners. In the case of single proteins having more than one active site [5], and membrane bound complexes made up of different protein molecules, intramolecular electron transfer is of prime concern, and the orientation of domains and molecules within these units is of considerable importance [15].