Plastocyanin algal, structure

From 13 completed amino-acid sequences and 54 partial sequences (>40 residues) of plastocyanins from higher plants it appears that sixty residues are invariant and 7 are conservatively substituted 02,7). With three algal plastocyanins included there are 39 invariant or conservatively substituted groups. It is believed that the same structural features apply to the whole family, and that highly conserved residues are an indication of functional sites on the protein surface. The upper hydrophobic and right-hand-side surfaces are believed to be particularly relevant in this context, the latter including four consecutive... 

Two features of the NMR structure present relevant new information. Phe-82 and Phe-29 are tyrosine and tryptophan, respectively, in the algal protein, and are apparently now, according to NMR, hydrogen bonded (internally) to each other. The deletion of the two residues 57 and 58 leads to an alteration of the shape of the acidic patch, a step back to the absence of the patch in evolutionarily more primitive plastocyanin. 

The first crystal structure information on a blue copper protein, for poplar plastocyanin in the Cu(II) state, was published in 1978 (2, 3). Since then, the Cu(I) state and related apo and Hg(II) substituted forms (5, 6), the green algal plastocyanin from Enteromorpha prolifera [Cu(II)] (7), azurin from Alcaligenes denitrificans [Cu(II) and Cu(D] (8, 9), azurin from Pseudomonas aeruginosa [Cu(II)] (10, 11), as well as pseudoazurin from Alcaligenes faecalis S-6 (12), and the cucumber basic protein, both in the Cu(II) state, have been published (13), making this one of the best-documented class of proteins. In addition, information as to three-dimensional structure in solution has been obtained from two-dimensional NMR studies on French bean and Scenedesmus obliquus plastocyanins (14,15). This review is concerned in the main with the active site chemistry. Other recent reviews are listed (16-20). 

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