The Photochemical Isomerization Kinetics of Urocanic Acid
and Their Effects Upon the In Vitro and In Vivo Photoisomerization
Action Spectra
Kerry M. Hanson and John D. Simon
The kinetic rate equation for the photoreversible photoisomerization between
trans-UA and cis-UA following absorption of UV radiation has been solved and
used to show that the maximum of the trans-UA photoisomerization action spectrum
depends upon both the initial trans-UA concentration irradiated in an experiment
and upon the irradiation dose used to determine the amount of cis-UA generated.
This kinetic model can be used to explain current discrepancies between in vitro
and in vivo photoisomerization action spectra reported in the literature.
Photochemistry and Photobiology, volume 66, p. 817 (1997)