THE BIOSYNTHESIS OF FERREDOXIN IN A CELL-FREE SYSTEM*

The investigation reported in this communication was concerned with the biosynthesis of ferredoxin in a cell-free system. A cell-free system, with the ability to incorporate amino acids into peptides and proteins, was developed from Cl. pasteurianum, and its requirements were established. After the incorporation of L-alanine-C14, ferredoxin-C14was isolated in crystalline form with the aid of added carrier ferredoxin. Amino acid analyses and absorption spectra strongly indicated that the isolated ferredoxin-C14, crystallized three times, was essentially free from impurities. Furthermore, experiments with Fe59strongly indicated that the iron may combine with the apoprotein after the latter is completely synthesized and released from the polysomes.