Regeneration of NADPH by Frozen-thawed Cells of a Blue-green Alga, Synechococcus sp.

Abstract

The photoreduction of NADP⁺ and its associated reactions were studied in a blue-green algal preparation that was frozen in liquid nitrogen and thawed at room temperature. The preparation was capable of photoreducing exogeneous NADP⁺. Water was the ultimate electron donor for the reduction. The optimum pH was 7.5-8.0, and optimum temperature, around 50°C. Light saturation for NADP⁺ photoreduction was reached at 50 μEinstein/m²/sec. Factors limiting the stability of the preparation were examined and a possible application of this cofactor regeneration system is discussed.