Figure 2.

Effect of increasing the BchD concentration on the lag phase of the magnesium chelatase reaction. All of the ingredients in a total volume of 500 μl (20 mM Tricine-NaOH at pH 9.0, 1 mM DTT, 4 mM ATP, 20 mM creatine phosphate, 25 units of creatine kinase, 20 mM MgCl₂, 5 μM deuteroporphyrin IX, 0.72 mg of BchH, and 0.42 mg of BchI) except BchD were prewarmed to 30°C in a fluorometer cuvette. BchD was added, and increase in fluorescence emission at 580 nm was monitored continuously for 30 min with excitation light at 408 nm.