FIGURE 5.

Substrate specificity of C. reinhardtii PFR1. The capacity of PFR1 to reduce methyl viologen (A) and to drive H₂ evolution by C. reinhardtii HYDA1 (B) using oxaloacetate or α-ketoglutarate was examined. The reaction mixtures contained 10 mm pyruvate, oxaloacetate, or α-ketoglutarate and 2 mm CoA in 100 mm potassium phosphate buffer, pH 6.8, and additionally 1.4 μm PFR1 and 10 mm methyl viologen (A) or 0.7 μm PFR1, 40 μm PETF, and 0.01 μm HYDA1 (B). A, methyl viologen reduction was determined spectrophotometrically. B, H₂ evolution rates were determined by gas chromatography as described in the legend of Fig. 4. The results shown are the means and standard deviations from two independent experiments carried out as technical duplicates.