Chemical Composition of Hair Melanosomes

Borovanská, J.; Duchoń, J

doi:10.1159/000251496

Cited by 7 publications

(1 citation statement)

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“…However, in the case of human iridal stroma melanosomes, the quantities of each of these constituents are not known. Although several studies have examined the protein content of melanosomes isolated from different human and animal tissue sources, the majority of these were based on melanosomes that had been isolated with acid/base extraction techniques. − This particular extraction method was widely used to extract melanosomes from tissue, but this approach is now known to both alter the physical and biological properties of the melanosome and result in isolation of a larger protein content than that associated with intact melanosomes …”

Section: Discussionmentioning

confidence: 99%

The Ultraviolet Absorption Coefficient of Melanosomes Decreases with Increasing Pheomelanin Content

Peles

Simon

2010

J. Phys. Chem. B

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Uveal melanosomes from the iridal stroma contain both eumelanin and pheomelanin, the ratio of which varies with iris color. Herein, we report the absorption coefficient at λ ) 244 nm for individual human iridal stroma melanosomes from dark brown and blue-green irides. The melanosomes are nearly identical in size, but differ in the relative concentration composition, ranging from a eumelanin/pheomelanin ratio of 14.8:1 (dark brown) to 1.3:1 (blue-green or hazel). The absorption coefficient of the melanosome decreases as its pheomelanin content increases. The origin of this decrease is attributed to a corresponding decrease in the number of UV-absorbing chromophores, reflecting the different molecular volumes of the monomeric building blocks of the two pigments. In agreement with reported data on synthetic pigments, the absorption coefficient of pheomelanin is found to be slightly larger than that for eumelanin at λ ) 244 nm (by a factor of 1.2). On the basis of the reported optical properties of synthetic models, this result suggests that the absorption of pheomelanin is less than eumelanin at wavelengths of biological relevance (∼315-400 nm).

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Section: Discussionmentioning

confidence: 99%