Sorry if this is an insulting question, but did you store it in enough glycerol to prevent it from freezing? Proteins don't like freeze/thaw cycles, especially slow ones.
________________________________ From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of jai mohan [00000cab66323371-dmarc-requ...@jiscmail.ac.uk] Sent: Tuesday, June 27, 2017 7:22 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Separating Monomers and Dimers Dear all, I am working on a Red Fluorescent Protein (His-Tag) molecular weight around 27kDa. After purification I ran a SDS page, the band at 27kDa confirms the monomer. The protein was stored at -20C, a week later again I ran a gel, this time I saw another new band between 50-60kDa, it confirms the protein solution contains both monomers and dimers. I would like to know, what is the best way to separate the monomers and dimers? One of my colleague advice me to go for sucrose gradient centrifugation and size exclusion chromatography. However, I seek all your valuable suggestions and advice. With best regards Dr. S.M.Jaimohan
