FIGURE 7.
Spectroscopic characterization of the reaction intermediates in the catalytic pathway of the POR enzyme from Synechocystis as detected by low temperature absorbance spectroscopy. The ternary complexes of Synechocystis POR (60 μm POR, 3.5 μm PChlide, 400 μm NADPH, 1 mm DTT in measuring buffer with 60% glycerol) were frozen at 180 K, irradiated by actinic light at λexc = 632 nm, and then the temperature was raised in the range between 180 and 305 K step by step. The absorbance spectra were monitored at the temperatures indicated in the insets. The figure reproduces the results reported in Refs. 6 and 30–32. It is shown to demonstrate that identical results are obtained under the experimental conditions used with the enzymes from barley.