Is there any appropriate way to remove L-arginine from a buffer? I need to measure protein concentration in a buffer containing L-arginine. As L-arginine interacts with bradford buffer (or in 280 nm with nanodrop) there is a need to remove L-arginine from the buffer. Note: the concentration of L-arginine which is present in the buffer is undetermined.
"As L-arginine interacts with bradford buffer (or in 280 nm with nanodrop) " did you try to measure and you got the reading for L-arg in the buffer (what was the blank there?). In other words, did you use your L-arg containing buffer as blank and tried to meausre your protein of interest, and got unusual values? I am just curious.
any desalting method will work, dialysis or any filter device (like Amicon or spin filters), depending on how many samples and how much of samples you have
Dialysis or desalting columns would seem to be the obvious first choice. I used to use a TFF device from Pall when I was refolding antibody fragments since I was working with larger volumes and needed to concentrate and change buffers at the same time.
"As L-arginine interacts with bradford buffer (or in 280 nm with nanodrop) " did you try to measure and you got the reading for L-arg in the buffer (what was the blank there?). In other words, did you use your L-arg containing buffer as blank and tried to meausre your protein of interest, and got unusual values? I am just curious.
Use a different protein assay method. BCA is common, fast and not sensitive to L-Arg
L-Arginine is offently used to increase the "solubility" of the protein. So be carefull as you are removing arginine to use adequate buffer (high ionic force, specific ions...)
Dear Ananda Ayyappan J.V, in fact the blank is the refolding buffer (containing urea, GSSG,GSH, Tris, EDTA and L-arginine), but I got unusual readings from bradford also in A-280 in nanodrop. I used L-arginine as blank, and it showed absorbance in bradford assay. But the problem is here that I have a sample protein in refolding buffer AFTER dyalisis, so I dont know the exact concentration of L-arginine in my present buffer. Also, I cant use millipore filters,because they are expensive. is there anything that I would use to precipitate the L-arginine and remove it?
I personally have no experience in refolding. But you are saying your protein is in a buffer where GSH,urea etc are there. How are you sure only L-arg making the noise?. May be other components such as GSH, urea may be responsible for the strong background signal.
I added the previous comment because I used L-arg-HCl (as a stabilizer) in my protein buffer without any issue, I could read with simple nanodrop. If you think L-arg is the only trouble maker, then (prepare a the same concentration you use) solution only with L-arg (not any GSH,urea added), use plain water as blank, and measure this L-arg solution as analyte. You may think of getting rid of this later.
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