J. R. Hwu et al. / Tetrahedron Letters 44 (2003) 2957–2960
2959
Scheme 2. Irradiation with UV light of a benzene solution an oxime ester 13 and 1,4-cyclohexadiene.
reactive p-cyano radical species contribute significantly
to the ability of 13 for its double-strand scission.
(pH 5.0–8.0, 0.10 M) in a Pyrex vial was preincubated at
37°C for 30 min. It was then irradiated with UV light
(312 nm, 16 W) under aerobic condition at room temper-
ature for 2.0 h. After addition of gel-loading buffer (2.5
mL containing 0.25% bromophenol blue, 0.25% xylene
cyanol, and 30% glycerol), the reaction mixture was
loaded on a 1% agarose gel with ethidium bromide
staining. The electrophoresis tank was attached to a
power supply at a constant current (ꢀ100 mA). The gel
was visualized by 312 nm UV transilluminator and pho-
tographed by FB-PDC-34 camera. Quantitation of DNA
cleavage was performed by integration of the optical
density as a function of the band area by use of a
Microtek scanner and NIH 1.60 image program.
Acknowledgements
For financial support, we thank the Ministry of Educa-
tion, the National Science Council of Republic of
China, and Academia Sinica.
References
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