Dissociating agents to prevent protein aggregation

[newera at plaza.snu.ac.kr]

I am purifying a small protein(mw 6100), which tends to aggregate well during its purification process although the completely purified product does not; so I think some dissociating agents is required to be added into the buffers used in the process. 
In choosing dissociating agents, some points should be considered :

1. My protein seems to be quite easily renatured, because the last step of its purification is reverse phase HPLC(water:acetonitrile) and freeze-drying. In addion, it has no cysteine.

2. I am using a cation exchange column(BioRex 70) and an affinity chromatography(Blue Sepharose); the less the agents affect the chromatographies, the better.

3. The buffer throughtout the process is 20mM Na phosphate, pH 6.8, no salt.


5% ethylene glycol is considered now. 
Is EDTA, DTT or 2-mercaptoethanol helpful?

If you give me any advice on this matter, I will much appreciate it.

Thanks.

Lee, Ji Hyun



--
email 	: newera at plaza.snu.ac.kr
address :
  Lee, Ji Hyun
  Laboratory of Physical Pharmacy(Prof. Lee, Bong Jin)

  Seoul National University
  College of Pharmacy		  
  Shinlim-Dong, Kwanak-Gu
  Seoul 151-742, Korea.