Editing Formaldehyde (section)

===[[Cross-link]]ing reactions===
Formaldehyde forms cross-links by first combining with a protein to form [[methylol]], which loses a water molecule to form a [[Schiff base]].<ref name="pmid26354429">{{cite journal | vauthors = Hoffman EA, Frey BL, Smith LM, Auble DT | title = Formaldehyde crosslinking: a tool for the study of chromatin complexes | journal = [[Journal of Biological Chemistry]] | volume = 290 | issue = 44 | pages = 26404–26411 | date = 2015 | pmid = 26354429 | pmc = 4646298  | doi = 10.1074/jbc.R115.651679 | doi-access = free }}</ref> The Schiff base can then react with DNA or protein to create a cross-linked product.<ref name="pmid26354429" /> This reaction is the basis for the most common process of [[Fixation (histology)#Chemical fixation|chemical fixation]].