EPR studies on the blue copper protein, rusticyanin: A protein involved in Fe 2+ oxidation at pH 2.0 in Thiobacillus ferro-oxidans

Abstract

Copper proteins may contain up to three different forms of copper, designated types 1,2 and 3 [ 11. Of the many copper proteins found in nature, one group which has been the focus of much recent attention is the blue copper proteins. Several blue copper proteins have been discovered, all characterised by an intense absorption around 600 nm and an unusual EPR spectrum, having a very small hyperfme splitting constant [2] . Blue copper proteins may contain one or more copper atoms per molecule (and one or more types of copper) but the intense blue colour and unusual EPR parameters are associated solely with the type 1 copper [3]. There are numerous blue proteins which contain only type 1 copper, e.g., azurin, stellacyanin, umecyanin and plastocyanln [2]. Although these proteins are basically similar with respect to their absorption