Hydrophobic interaction question

kaj.stenberg at helsinki.fi.invalid kaj.stenberg at helsinki.fi.invalid
Tue Apr 6 07:23:46 EST 2004

I have a question regarding Hydrophobic interaction (HIC).

I am attempting to use an octyl sepharose 4 fast flow column as one
isolation step (between ion exchange and gel filtration).

In a pilot experiment the buffer was 20mM tris - 50mM NaCl - 2mM
ZnCl2 - 1.7 M NH4SO4, pH 8.0. Higher ammonium sulfate precipitates my
protein. In this case some half of the protein came straight through, 
half could be eluted from the column with a gradient to 0M NH4SO4.

Question: replacing the NH4SO4 with NH4PO4 would decrease the chaotropic
effect, but also increase the salting-out effect. Could I hope to gain
anything at all regarding binding, and can anything be said before 
testing? (I will also play some with the pH of the solution (7.5 as a 
first test)).

any help appreciated,
Kaj Stenberg

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