Photoreduction of NADP + sensitized by synthetic pigment systems

Two synthetic pigment systems capable of enzymatically photoreducing NADP(+) are described. One system contains proflavine; the other, acridine. The complete system consists of ethylene diamine tetraacetic acid (EDTA), proflavine (or acridine), ferredoxin-NADP reductase (EC 1.6.99.4), and NADP(+). The two pigments initiate the photoreduction of NADP(+) in different portions of the electromagnetic spectrum. Proflavine photosensitizes in the visible portion; acridine, in the ultraviolet. Neither proflavine nor acridine is structurally related to chlorophyll. The acridine system has the attractive property that the enzyme, ferredoxin-NADP reductase, is the only component of the system that absorbs appreciably in the visible region of the spectrum.