A new assignment of the disulfide linkage in stellacyanin.
Which cysteine of apostellacyanine reacts with 4-vinylpyridine in 6 M guanidine-HC1 depends upon the pH. We infer that a disulfide switch occurs at higher pH and that in the native protein the disulfide bridge occurs between Cys-59 and Cys-93. Thus Cys-87, which is homologous to the cysteine ligands of azurin and plastocyanin, is available to bind copper.
D000595:Amino Acid Sequence; D003545:Cysteine / Q000032:analysis; D004220:Disulfides / Q000032:analysis*; D008667:Metalloproteins / Q000032:analysis*; D010940:Plant Proteins / Q000032:analysis*
D004220:Disulfides; D008667:Metalloproteins; D010940:Plant Proteins; C003343:stellacyanin protein, plant; D003545:Cysteine