Protein labeling by reductive methylation with sodium cyanoborohydride: Effect of cyanide and metal ions on the reaction
✍ Scribed by Neil Jentoft; Dorr G. Dearborn
- Publisher
- Elsevier Science
- Year
- 1980
- Tongue
- English
- Weight
- 415 KB
- Volume
- 106
- Category
- Article
- ISSN
- 0003-2697
No coin nor oath required. For personal study only.
✦ Synopsis
have demonstrated that reductive methylation with labeled formaldehyde and NaCNBH, provides a simple method for specifically labeling the amino groups of proteins using extremely mild reaction conditions. However, cyanide, which is one of the products of the reaction, reduces labeling efficiency by reacting with formaldehyde to form the formaldehyde cyanohydrin addition product. Certain transition metal ions are able to prevent this secondary reaction by forming stable coordination complexes with cyanide. Inclusion of millimolar quantities of Ni(I1) in reaction mixtures leads to a 20-30% increase in protein labeling so that maximal derivatization of amino groups can be realized with only a 3-to 4-fold ratio of formaldehyde to amine rather than the 5-to lo-fold excess necessary in the absence of metal ions.