His-tag is close to neutral but flag-tag is acidic.
Using flag-tag for affinity purification usually gives cleaner protein but it costs a fortune due to low binding capacity of commercially available anti-flag resins. --Chun From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Harman, Christine Sent: Tuesday, April 19, 2011 11:11 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Flag tag vs. his-tag Hi all, I am trying to decide between using a N-term his-tag or an N-term flag tag to be expressed on a protein that I will eventually want to try and crystallize. I usually don't cleave my tags unless absolutely necessary and I want to avoid double tagging. I am leaning towards the flag since from my experience this tag is good for protein interactions (pulldowns), but I don't know the effects of a flag tag in crystallization trials. Does anyone have experience with crystallizing protein with flag tags? Thanks, Christine
