Dear Saeed: It depends on the composition of the broth, the ionic/physical
characteristics of the peptide. If there are strong charges on the
peptide, one can use Dowex-type ion exchagers, but crud from the broth will
affect this type of chromatography if one uses supplemants like Yeast
extract, tryptone etc. Alternatively, you could subject the culture
supernatant to a heat-shock, eg 70 C for about 5 to 10 minutes, spin out
the precipiates and use the clarified supernatant for purification, of
course the peptide has to be stable to such treatment. The list can go
longer, but the choice will be dictated by the growth medium and peptide
characterisitcs, however, you will need a good bulk bacth first step to
enrich for peptide realtive to other components. Good luck, gautam
Gautam Sarath
N-226, Beadle Center
Protein Core Facility - Center for Biotechnology &
Department of Biochemistry
University of Nebraska-Lincoln
Lincoln, NE 68588-0664
Phone: 402-472-2928
FAX: 402-472-7842
http://www.biotech.unl.edu/Proteins/index.html