A synthetic analogue for the active site of plant-type ferredoxin: two different coordination isomers by a four-cys-containing [20]-peptide.
The (Fe2S2)2+ complex of an artificial 20-peptide ligand, Ac-Pro-Tyr-Ser-Cys-Arg-Ala-Gly-Ala-Cys-Ser-Thr-Cys-Ala-Gly-Pro-Leu-Leu-T hr-Cys- Val-NH2, containing an invariant Cys-A-B-C-D-Cys-X-Y-Cys (A, B, C, D, X, Y = amino acid residues) fragment of plant-type ferredoxins was synthesized by a ligand exchange method with [Fe2S2(S-t-Bu)4]2-. 1H-nmr spectroscopic and electrochemical data of the complex indicate the presence of two coordination isomers. One of them having a Cys-X-Y-Cys bridging coordination to the two Fe(III) ions, has the (Fe2S2)2+ core environment similar to those of the denatured plant-type ferredoxins and exhibits a positive shifted redox potential at -0.64 V vs saturated colonel electrode (SCE) in N,N-dimethylformamide (DMF). Another isomer with the Cys-A-B-C-D-Cys bridging coordination shows a negative redox potential at -0.96 V vs SCE in DMF.
Ueyama
N
N
Department of Macromolecular Science, Faculty of Science, Osaka University, Japan.
Ueno
S
S
Nakamura
A
A
Wada
K
K
Matsubara
H
H
Kumagai
S
S
Sakakibara
S
S
Tsukihara
T
T
D000595:Amino Acid Sequence; D001665:Binding Sites; D003545:Cysteine / Q000737:chemistry*; D005288:Ferredoxins / Q000138:chemical synthesis*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis; D010940:Plant Proteins / Q000138:chemical synthesis*
D005288:Ferredoxins; D010446:Peptide Fragments; D010940:Plant Proteins; D003545:Cysteine