Absorbance and fluorescence emission spectra of in vitro bilin
addition reactions with CpcS-I and HT-CpcU and rCpcBA. A,
absorbance spectra of reactions with rCpcBA alone (control, solid
line) and rCpcBA with CpcS-I alone (dash dots), HT-CpcU alone
(long dashes), or CpcS-I and HT-CpcU copurified (long dash triple
dot). The absorption maxima of some reaction products are indicated.
B, fluorescence emission spectra of the same reactions with
excitation at 590 nm (10-nm slit widths). The fluorescence emission maximum
for rCpcBA with CpcS-I/HT-CpcU was at 643 nm, whereas all products had
emission maxima between 650 and 660 nm.