Biophysical Chemistry

Temple University Department of Chemistry

Fluorescent nucleic acid base analogs

We use molecules like 2-aminopurine and 6MAP, fluorescent adenine analogs, to measure the conformational changes that occur upon substrate binding in photolyase. We also study the basic photophysical properties of the analogs using a variety of techniques.

The difference charge distribution for 2-Ap is well supported by TD-DFT calculations

The fluorescence of 2-aminopurine (2-Ap)  quenches when it is incorporated into the DNA double helix. However, when a dsDNA strand with a 2-Ap opposite a thymidine dimer is bond, the helix is perturbed and the 2-Ap lights up!

 

We obtained the excited state charge distribution for 2-Ap using Stark spectroscopy:

These spectra were used to produce the assignments shown to the right