ion exchanger questions

[nulliespooner]

Hello everyone

I am a biology student and in out protein seperation course we did seperation on an ion exchanger

first we washed the column 10 times with the buffer and then loaded our protein sample.

after loading the sample we collected the volume eluted from the column into a "wash fraction".

I have no idea why we did that... what could possibly be the reason to collect this fraction?

it is not for positive protein (eluted at 0 mM NaCl)... so what then?

why do we do it? and what is in there?

Thanks!!!!

[nulliespooner]

[BabcockHall]

Was the sample a mixture of proteins or a single protein? Saving that fraction is always a good idea.

Edited May 21, 2013 by BabcockHall

[alibaba441]

if there are a mixture of proteins they will be eluted at different concentrations of NaCl depending on their affinity for the chromatography media. hene you keep all of the wash from the column to analyse later to see which protein was eluted at which concentration.