FIG. 2.

Reduction of amaranth by cell extracts from E. coli K38(pEE1001) under aerobic (□, ▵) and anaerobic conditions (■, ▴). The reaction mixtures contained (per milliliter) 50 μmol of NaK phosphate buffer (pH 7.7), 0.4 μmol of NADH, 0.1 μmol of FAD, and 0.05 μmol of amaranth. The reactions were started by the addition of 20 μl of a cell extract from E. coli K38(pEE1001) (88 μg of protein), and the decrease in absorbance was simultaneously determined spectrophotometrically at λ = 340 nm (■, □) and λ = 520 nm (▴, ▵). For the reaction under anaerobic conditions, all solutions were made anaerobically by repeated gassing with N₂, and the reaction was performed in gastight cuvettes.