Protein-formaldehyde reactions

Figure 3.1 Two essential steps of chemical reaction of formaldehyde (HCHO) with nucleic acid exemplified by adenine that are similar to formaldehyde-protein reactions, (a) Addition reaction as the first step, resulting in a methylol derivative, methylol adenylic acid (b) Second step is a condensation reaction, a stable product methylene-bis-adenylic acid is derived between the methylol derivative and another adenine. Reproduced with permission from Shi et al.,AIMM 2001 9 107-116. 

Protein Fibers. Reaction with formaldehyde hardens proteins, decreases their water solubihty, and increase. their resistance to chemical reagents. The nature of the formaldehyde-protein reactions which produce these results ha.s ahead) been discussed fpages 221-224 . These same reactions are responsible for the modifying action of formaldehyde and reacth e formaldehyde deri at-h es on, protein fillers and related fibers containing amido and amino radicals. 

Metz B, Kersten GFA, Hoogerhout P, et al. Identification of formaldehyde-induced modifications in proteins reactions with model peptides. J. Biol. Chem. 2004 279 6235-6243. 

These initial findings do not exclude other possible formaldehyde-induced reactions with tissue proteins. Notably, this first model system was not designed to detect the role of lysine residues. Lysine has a propensity to react with and form a variety of different types of cross-links with other amino acids in the presence of formaldehyde.1,3 417 Therefore, it is likely to also be important in reactions with formaldehyde. In fact, peptides with internal lysine residues were purposefully excluded from this initial study for technical reasons. To explore the importance of lysine residues in antigen retrieval, an alternative method was employed. 

Metz B, Kersten GFA, Baart GJE, de Jong A, Meiring H, ten Hove J, van Steenbergen MJ, Hennink WE, Crommelin DJA, Jiskoot W. Identification of formaldehyde-indnced modifications in proteins Reactions with insnlin. Bioconjng. Chem. 2006 17 815-822. 

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