Mavicyanin, a stellacyanin-like protein from zucchini peelings: primary structure and comparison with other cupredoxins.
The complete amino-acid sequence of mavicyanin, a small blue copper-containing glycoprotein isolated from zucchini peelings, is presented. The sequence of this cupredoxin was deduced from analysis of peptides obtained after cleavage of the protein with trypsin or Asp-N endoproteinase. Mavicyanin consists of a single polypeptide chain of 108 amino-acid residues. Accurate molecular weight determination by electrospray mass spectrometry (12 752 Da) indicates a mass difference of approx. 1005 Da with respect to the mass of the protein, as determined on the basis of the amino-acid sequence (11747 Da). This difference was tentatively assigned to the carbohydrate moiety, not yet characterized, attached to the protein via an N-linkage to Asn-58 and O-linkages to unidentified Ser/Thr residues. The comparison of the primary structure of mavicyanin with those of other cupredoxins shows that three copper ligands (His-44, Cys-57 and His-90) are conserved, while a glutamine residue (Gln-95), as in stellacyanin, is possibly the fourth ligand. An amino-acid sequence alignment of mavicyanin with copper proteins currently identified as phytocyanins is also proposed, showing same invariant residues in key positions related to the maintenance of the beta-barrel fold and to the active site.
Schininà
M E
ME
Dipartimento di Scienze Biochimiche Alessandro Rossi Fanelli, Università La Sapienza, Roma, Italy. schinina@caspur.it
Maritano
S
S
Barra
D
D
Mondovì
B
B
Marchesini
A
A
D000595:Amino Acid Sequence; D001400:Azurin / Q000031:analogs & derivatives* / Q000737:chemistry; D003300:Copper; D008024:Ligands; D013058:Mass Spectrometry; D008667:Metalloproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014675:Vegetables / Q000737:chemistry*
D008024:Ligands; D008667:Metalloproteins; D010940:Plant Proteins; C050107:cupredoxin; C022828:mavicyanin protein, Cucurbita pepo; D001400:Azurin; C003343:stellacyanin protein, plant; D003300:Copper