Photochemical reduction of triphosphopyridine nucleotide by cell-free extracts of blue-green algae

Abstract

THE photochemical reduction of triphosphopyridine nucleotide (TPN) by extracts of photosynthetic organisms has been shown to be catalysed by a protein factor, photosynthetic pyridine nucleotide reductase (PPNR)1. PPNR has been detected in a variety of higher plants, algae and photosynthetic bacteria1,2. It has been shown2 to be similar to, but not identical with, the electron transport factor ferredoxin which has been isolated from several non-photosynthetic bacteria3. Thus far, however, PPNR has not been demonstrated in blue-green algae. Indeed, it has not proved possible to obtain cell-free TPN reduction by these organisms4 although spectroscopic studies on whole cells5 have shown that endogenous pyridine nucleotides undergo oxidation-reduction changes under illumination. In this communication, we report the isolation and purification of PPNR from a blue-green alga and also a method of obtaining photochemical TPN reduction in a cell-free system. © 1963 Nature Publishing Group.