Complete amino acid sequence of poplar plastocyanin b

A second type of plastocyanin, plastocyanin b (PCb) was isolated from leaves of poplar Populus nigra var. Italica. The complete amino acid sequence of 99 residues in the single polypeptide chain of plastocyanin b has been determined: DVLLGADDG SLAFVPSEFS GEKIVFK NNAGFPHN FDED PSGV D SKISMSEE DLLNAKGETF EVALS KGEY FYCSPHQGA GMVGKV VN The sequence obviously demonstrates, that PCb, in comparison with the known plastocyanin, plastocyanin a (PCa), has 12 amino acid replacements (underlined letters): Ile 1→Val, Ile 21‐Ser 22‐Pro 23→Val‐Pro‐Ala, Ile 39‐Val 40→Val‐Leu, Ser 45‐Ile 46→ Ala‐Val, Ala 52→Val, Asn 76→Asp, Ser 81→Thr and Thr 97→Ile. The replacements at positions 40 and 76 of PCb are probably essential for differences in its redox and electrochemical properties, respectively.