Is it better to use methanol-free formaldehyde for DNA-protein crosslink?
Yes, it can. When the famous reaction in forming "pheno-formaldehyde resins" starts, the following occurs initially:
HO-C6H5 + H2-C=O → HO-C6H4-CH2OH
The product is called methylolphenol. When the reaction proceeds, there can be 2 & up to 3 (-CH2OH) substituents on the benzene ring.
Now, these groups "which are similar to CH3OH" are the ones which participate in forming the cross-links in several condensation reactions providing -CH2- as bridges between monomers & leading eventually to cross-linked 3-D structure (as in Bakelite).
The use, of formaldehyde alone or with methanol, will depend upon the sites that will be linked. If you want to link C=C with another C=C, then other reactants can do the job.
Dear Nizar,
thank you very much! It is really useful information for me. So if I want crosslink DNA with protein, where Shiff Base occurs (CH2-N), shoud I use formaldehyde without methanol? If I understand well...?
A Schiff base (or an imine) results from the reaction of an aldehyde or ketone with a primary amine. Reacting an aldehyde with 1o amine will proceed as follows:
-C=O + H2N-R → -C=N-R +H2O
It has been found that little H+ "few drops" can help this condensation reaction.
3 years ago, one of our Research Gate colleagues asked a good question about conditions in reactions that form Schiff bases & he received good answers.
https://www.researchgate.net/post/What_are_the_conditions_used_for_schiff_base_reaction
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