SDS quantitation and removal with resins

Scott Coutts scott.coutts at med.monash.edu.au
Tue Jul 8 08:08:51 EST 2003


Hi Frank,

Frank R. Gorga wrote:

 >
> Could the Pierce reagent simply be a solution of KCl or KAc?
> 

Yeah, some others have suggested that, and that's what I had suspected. 
But we dotn have any, and I've never used it! So I was wondering if 
anybody knew for sure.

>
> Potassium dodecyl sulfate is fairly insoluble in water. Thus one can remove
> most of the "SDS" from a solution simply by adding  ~0.75 M K+ to a sample.
> I do not have a clue what the final concentration of detergent will be... it
> will vary greatly with other components present. But it might work in your
> application.
> 
> As for using various resins... all have the potential problem of absorbtion
> of the protein of interest to the resin. This is not usually an
> insurmonttable problem, just beware. (I have had good luck in reducing loss
> of protein when removing non-ionic detergents using "Biobeads" by adding
> "extra" lipid to the mix. Not an ideal fix, but one does what one has to!)
>

Yeah, I have used biobeads and an amberlite xad with quite a lot of 
success, but that was with Triton X-114. I didnt know if it worked with 
SDS as well.

 >
> As for quantitation of detergents... not easy! The fluorescence assays,
> while they work well to measure CMC in a simply solution are not specific
> enough for a sample containing biological molecules.
>

No, I had expected that it wouldnt be good enough for what I want but I 
think there isnt really a method that is.

>
> In the "old days" (late 70's), one could by radiolabeled SDS and TX-100 from
> NEN. (I don't know if they are still available.) This was the simplest way
> to follow the removal of detergent... add a 1000 cpm / uL of 3H-detergent to
> the starting sample and count small samples along the way.
>

Yeah, I know you can buy radiolabelled SDS from Sigma, but I cant really 
do that. It has to be 'normal' SDS.

Thanks anyhow.





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