buffer for CD - (Aug/23/2007 )

hi..
i need to do CD of my protein. protein is quite stable in 50mM Nah2po4 (ph 7.4) and 300mM Nacl. but in this buffer i am getting a lot many noisey signal in CD because of Nacl ( i think). when i changed buffer to low ionic strength 10mm nah2p04 (without nacl), and then pass through gel filtration chromatography, i could not see any peak , so i think potein precipitate. i tried with different buffer -10mm Na2so4, 10mm Amm. acetate. all the time i faced the same problem.
what are the other buffers for CD?? which salt can be used for CD?? by the way, i am doing Far UV CD??

thanks

you are probably seeing non-specific binding to the matrix in gel filtration rather than precipitation. you can try dialysis but it may still exhibit some non-specific binding to the membrane.