Total synthesis of a miniferredoxin.

A miniferredoxin has been designed based on the Desulfovibrio gigas ferredoxin II structure and has been successfully synthesized. The 31 amino acid apoprotein was synthesized via standard Fmoc solid phase peptide synthesis and in vitro cluster insertion carried out. The UV-visible spectrum of the miniferredoxin (peak at 300 nm and a shoulder at 405 nm) shows the same features as that of the D. gigas ferredoxin. Cyclic voltammetry indicated a quasireversible electrode process with a midpoint potential of -370mV vs NHE, which demonstrates that the miniferredoxin is redox active. From these and EPR studies, we propose the incorporation of a Fe4S4 cluster.