Raper-Mason-pathway

The current melanin biosynthesis pathway is described as the Raper-Mason pathway.

The current understanding of melanin is based on the generally accepted biosynthetic pathway for polymerization, the Raper-Mason pathway (RMP), which was first published in 1948. The pathway describes the stepwise evolution of melanin from the essential amino acid L-tyrosine via dopaquinone to dihydroxyindole (DHI) or dihydroxyindolecarboxylic acid (DHICA). These units are then oxidized to form indole-5,6-quinone-2-carboxylic acid (IQCA) or indole-5,6-quinone (IQ), the immediate precursors for polymerization. In addition to the various structural complexities, melanogenesis processes in vivo are regulated by a number of enzymes, including tyrosinases and decarboxylases, which link the oxidative and decarboxylative steps.

1. Casanola-Martin GM et al. (2014) Tyrosinase enzyme M. R. 1. An overview on a pharmacological target. Curr Top Med Chem 14:1494-1501.
2. Mason HS (1948) The chemistry of melanin; mechanism of the oxidation of dihydroxyphenylalanine by tyrosinase. J Biol Chem 172:83-99.

3. Ni QZ et al. (2020) Chemoenzymatic elaboration of the Raper-Mason pathway unravels the structural diversity within eumelanin pigments. Chem Sci 11:7836-7841.

4. Raper H S (1928) The Aerobic Oxidases. Physiol Rev 8:245-282.