Ferredoxin is a constitutent of

Ferredoxin is a constituent of PS I.
Ferredoxins are nonheme-iron-containing proteins and are mainly found in anaerobic bacteria and chloroplasts.
Ferredoxin and flavodoxin are soluble proteins that are reduced by the terminal electron acceptors of photosystem I.
When NADP⁺ and a suitable enzyme are present, two ferredoxin molecules, carrying one electron each, transfer two electrons to NADP⁺, which picks up a proton and becomes NADPH.