|MadSci Network: Microbiology|
I did a quick search in the scientific literature for the kinetics (kinetics is the term used when describing the catalytic specifics on an enzyme) of rad proteins. I could not find anything, however have you tried posting your question on the newsgroup bionet.microbiology on USENET? Someone who works in UV damage in prokaryotes, who follows the newsgroup, may have a specific answer.
The best I can do is to answer your question vaguely. In optimal conditions an enzyme will carryout its catalytic function in terms of microseconds (1.67 microseconds for carbonic anhydrase) to milliseconds (DNA polymerase I catalysis one reaction in 66 milliseconds). So when a rad protein complex encounters a thymine dimer the repair is virtually instantaneous, under optimal conditions.
The reaction rate examples used in this answer were taken from Biochemistry, L. Stryer, 1988, W.H. Freeman and Company, NY, USA.
Try the links in the MadSci Library for more information on Microbiology.