GENETIC AND MOLECULAR ANALYSIS OF DNA DAMAGE REPAIR AND TOLERANCE PATHWAYS - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 113

They then hypothesized that if the altered Norin 1 photolyase formed stable E-S
complexes more slowly, the complexes that were eventually formed might be less
stable than those from Sasanishiki. They added cell extracts from Norin 1 or from
Sasanishiki to UV-irradiated DNA in vitro, and incubated the mixes in the dark to allow
Figure 14. Measurement of photolyase-dimer complex stability by photoflash analysis.
complexes to form. They then incubated aliquots of the complexes at different
temperatures, and as a function of time after complex formation, administered one
saturating photoflash to allow photolysis of all existing photolyase-CPD complexes.
Figure 15. Determination of photolyase-dimer complex stability in extracts of Norin 1 and Sasanishiki at 0,
28, 45 and 60°C.
The resulting data clearly showed that the E-S complexes formed by the Norin
photolyase were less thermostable than those from Sasanishiki, strongly suggesting that
the Norin 1 photolyase gene has a mutation, most probably a mutation in its structural
gene that affects photolyase function.