The Primary Structures of Pseudomonas AM1 Amicyanin and Pseudoazurin. Two New Sequence Classes of Blue Copper Proteins

The amino acid sequences of two blue copper proteins from the pink facultative methylotroph Pseudomonas AM1 (N.C.I.B. 9133) were determined. They each consist of a single polypeptide chain and bind one copper atom. Amicyanin contains 99 and pseudoazurin 123 residues. Copper-binding sites, consisting of the side chains of two histidine, one cysteine and one methionine residues, can be recognized in each protein by analogy with azurin and plastocyanin, but the spacings of the ligand residues are different, and other sequence similarity is limited. Proteins that are in the pseudoazurin sequence class can be recognized in some strains of Alcaligenes, and probably also in Paracoccus denitrificans. Detailed evidence for the amino acid sequences of the proteins has been deposited as Supplementary Publication SUP 50130 (23 pp.) at the British Library (Lending Division), Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1985) 225, 5.