Reductive methylation of proteins with sodium cyanoborohydride. Identification, suppression and possible uses of N-cyanomethyl by-products.
Reductive methylation of protein amino groups with formaldehyde and sodium cyanoborohydride is shown to give up to 25% yield of N-cyanomethyl (-CH2CN) product; on work up of the reaction this is hydrolysed back to starting amine, lowering the methylation yield. Addition of metal ions such as Ni2+, which complex with free cyanide ion, improve reductive methylation yields by suppressing by-product formation. The N-cyanomethyl group itself, produced in good yield when cyanide ion replaces cyanoborohydride, may have some value as a reversible modifier of amino groups in proteins.
D001894:Borohydrides; D055598:Chemical Phenomena; D002621:Chemistry; D008745:Methylation; D009570:Nitriles / Q000032:analysis*; D010084:Oxidation-Reduction; D011506:Proteins
D001894:Borohydrides; D009570:Nitriles; D011506:Proteins; C009282:sodium cyanoborohydride