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Optical Absorption of Melanin

by Steven Jacques, Oregon Medical Laser Center
Fig. 1

The building blocks of eumelanin and pheomelanin. Curly red lines indicate sites of attachment to the extended polymer and possibly to proteins. The details of these attachments in the total complex structure are not known. Click here to see synthesis of melanin from tyrosine or DOPA.

Chemical structure

Melanin is a very complex absorbing material. Melanins from natural sources fall into two general classes:

The melanins are considered to be polymers of the basic building blocks shown in Fig. 1. However, the details of the polymerization and the role of protein linkages in the natural melanin complex are not known. Although the widespread belief is that the insoluble eumelanins are highly polymeric cross-linked structures consisting of several hundred monomeric units, Prota et al. (1988) point out that this belief is based on still ambiguous evidence.

REFERENCE: G. Prota, M. D'Ischia, A. Napolitano, The chemistry of melanins and related metabolites, in "The Pigmentary System", ed. JJ Nordlund et al., Oxford University Press, 1988.

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