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. Author manuscript; available in PMC: 2012 Jun 30.
Published in final edited form as: Chem Biol Interact. 2011 Jan 13;192(1-2):118–121. doi: 10.1016/j.cbi.2011.01.006

Figure 2.

Figure 2

Reactivity of 3,4-dihydroxyphenylacetaldehyde (DOPAL) involves modification of protein amines via the aldehyde. However, catechol oxidation is possible, yielding a thiol-reactive quinone, and such oxidation may explain the protein cross-linking observed for DOPAL. The spontaneous reaction of the DOPAL aldehyde with a protein primary amine (e.g., Lys) may yield a Schiff base as shown or an enamine product. Auto-oxidation of the DOPAL catechol, which is known to occur for DA, or enzyme-mediated oxidation (e.g., tyrosinase, prostaglandin-H-synthase) is predicted to result in formation of an ortho-quinone, which are known to be highly reactive for protein thiols (e.g., Cys).