Two Phase Separation

[A. J. Bowling]

hello all,

i am trying to obtain some plasma membrane using an aqueous two phase system 
containing dextran and peg.  everything is fine until i put my microsomal 
fraction onto the two phase mixture and mix them.  no amount of centrifugation 
or sitting at 4 deg. will cause the two phases to separate again.  does anyone 
know what is going on here?  

thanks for taking the time to read this.  believe me, any help will be greatly 
appreciated.


andy b