How to get pure protein of a gene - (May/02/2012 )

i m working for expression of protein.my problem is that there is an extra chunk of protein .how can i separate it to get pure protein of my gene .

extra chunk? I assume you ran your purified protein on a gel and you are getting multiple bands. The best way to get the protein that you want from this mixture is size exclusion by FPLC. See if you have a column available and try that.