Fluorescence of catechol amines and related compounds condensed with formaldehyde.
The reaction under mild conditions between formaldehyde and phenylalanine and phenylethylamine derivatives has been studied. When the amines included in a dried protein film were exposed to formaldehyde vapour a very intense green to yellow fluorescence was given only by those that as well as being primary amines also have hydroxyl groups at the 3 and 4 positions (3,4-dihydroxyphenylalanine, dopamine, noradrenaline). The 3-OH group seems to be essential for the reaction. The catechol amines, which are secondary amines (adrenaline, epinine), gave a much weaker fluorescence that developed more slowly. The results obtained on further examination of the reaction favour the view that the amines primarily condense with formaldehyde to 1,2,3,4-tetrahydroisoquinolines which are involved in a secondary reaction to become highly fluorescent and at the same time insoluble. This secondary reaction may be a binding to protein, an oxidation with the formation of double bonds in the heterocyclic ring, or both.
D002395:Catecholamines / Q000097:blood*; D004298:Dopamine / Q000097:blood; D004837:Epinephrine / Q000097:blood; D005404:Fixatives; D005557:Formaldehyde; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence / Q000379:methods*; D009638:Norepinephrine / Q000097:blood; D013696:Temperature
D002395:Catecholamines; D005404:Fixatives; D005557:Formaldehyde; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine