I'm running a quantitative proteomics experiment on biotynylated proteins (using BioID approach, followed by streptavidin pulldown). I'm planning to use reductive methylation (formaldehyde and sodium cyanoborohydride) for labelling and comparing control and experimental samples. I just noticed biotin has a urea like backbone (-NH-CO-NH-)... does anyone know if these N are suceptible to methylation reaction?? my chemistry is rusty?
Thanks
Alex
The backbone of biotin is very much like the peptide bonds that link amino acids together in a polypeptide chain. You may well recall that the peptide bond is quite robust and relatively difficult to break due to its partial double bond character (try to draw resonance structures for it, where the C=O assumes a C-OH character, while the -NH- assumes a =N- character). This resonance phenomenon gives added stability to the -NH- group and will render it stable enough to withstand methylation (i.e., it is not possible to methylate =N-). HTH.
Thank you Vicente!!! I will go ahead with the experiments. I hope no unexpected 'side' reactions :-)
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