Dear Zhe,

For DNA Protein interaction study you can target transcription factors or DNA Polymerase. DNA polymerase are easily available in PCR reagents and you can isolate DNA from any bacteria, plant sample or animal cell sample. I think its most common DNA-Protein interaction study.

After the Polymerase-DNA interaction you can freeze or fix the sample. This will be most approachable method if you are interested to know crystallization study of DNA-Protein complex.

Best Regards

Piyush

Thank you for your advice, Piyush! I will have a look at both polymerase and transcription factors!