[Porkodi]

Hi all!

I have few issues in DNA coupling reaction with ethylene glycol diglycidylether. First thing is, we have in our lab DNA sperm from salmon. In the literature they used sodium salt of DNA. so first can anyone help me how to get Na-DNA from DNA sperm? many thanks in advance!

[Babcock_Hall]

Does the DNA from salmon specify anything about the counterion that is present? 

[Porkodi]

I do not think so. FYI the CAS is 100403-24-5.
and thanks for your interest!

[Babcock_Hall]

Unless one were to isolate DNA at low pH (which seems unlikely), the DNA will always have a counterion, but it is not clear to me that the counterion must always be Na.  Quite the contrary, I seem to recall using other counterions (potassium or lithium) in a previous life, when I isolated bacterial DNA.  I looked at the Sigma Aldrich page on what I took to be your product briefly, but I did not see anything about which counterion is present.

http://www.sigmaaldrich.com/catalog/product/sigma/d7290?lang=en&region=US

I hope that someone with more direct experience than I have can provide some enlightenment.

[Porkodi]

Thanks again for your time looking into details!

[Yggdrasil]

Why do you think you think using the sodium salt would improve the procedure versus using the DNA you currently have?  Are there other parts of the coupling reaction that you might need to improve?

If you really think you need the Na salt, sigma sells salmon sperm DNA that is explicitly labeled as a sodium salt (sigma aldrich cat# D1626).

[Porkodi]

Hi!

That is a interesting question for that I would like to know the answer! I tried to have coupling reaction of DNA with polyethyleneglycoldiglycidylether (p-EGDE) expecting to have hydrogel at 50 deg C in presence of TEMeD catalyst. But unfortunately I didnt get the product what i expected. So while I was looking for answers i found that in all the literatures they used Na salt of DNA. And of course I already processed to buy that. But meanwhile I would like to understand the chemistry behind it. So can you help me what was going on with it?

[Babcock_Hall]

One thing you could do is to contact the supplier of what you do have and ask them what the counterion is.  The counterion issue may or may not be significant.  Can you provide some more information on the coupling reaction itself?  This is just a guess but pH, for example, can often be very important in chemical modification of proteins.  Without knowing the specifics of the chemistry, I cannot say too much.  Here is an abstract I found:
http://www.ncbi.nlm.nih.gov/pubmed/19658412