The amino acid sequence of ferredoxin-NADP+ oxidoreductase [EC 1.18.1.2, FNR] from Spirulina sp., a blue-green alga, was determined. Spirulina ferredoxin-NADP+ oxidoreductase was composed of 294 amino acid residues and the molecular weight of the holoenzyme was 34,135. An apparent homology of the