Figure 6.

Demonstration of blue-light reversible CO inhibition of the costunolide synthase. Product formation in the presence of 90% (v/v) N₂ + 10% (v/v) O₂ (labeled as −CO) is set at 100% and this activity corresponds to a peak size of dehydrosaussurea lactone (16) (costunolide), saussurea lactone (18) (dihydrocostunolide), and leucodin (19) of 0.58, 0.27, and 0.15 × internal standard (1 nmol of cis-nerolidol) respectively. The inhibition in the presence of 90% (v/v) CO + 10% (v/v) O₂ (labeled as +CO) was reversed to some extent by irradiation with blue light (450 nm). All incubations were done in the absence of FAD and FMN.