According to recent theory on the structure of melanin, the sulfur content of melanin is a reflection of the amount of cysteine used in its manufacture. We compared the sulfur contents of melanins from hair, choroid, iris, and retinal pigment epithelium from black-haired cattle and separately from red-haired cattle. In black-haired cattle, sulfur contents of hair and ocular melanins were all be...

Melanins are polymorphous and multifunctional biopolymers with a relatively high concentration of free radicals. EPR spectroscopy was used to study o-semiquinone free radicals in model eumelanins synthesized from 3,4-dihydroxyphenylalanine (DOPA) and tyrosine in the presence of tyrosinase, and melanins isolated from A-375 and G-361 human melanoma malignum cells exposed to two compounds: 5,7-dim...

Melanins are ubiquitous in nature but their biological activities and functions have been difficult to discern. Conventional approaches to determine material function start by resolving structure and then characterize relevant properties. These approaches have been less successful for melanins because of their complex structure and insolubility, and because their relevant properties are not rea...

Melanins can be obtained by chemical and microbiological synthesis, or by extraction from animal and plant tissues. One of the major problems in studying melanins, is the lack of adequate methods for the isolation of pure melanin pigments. Remarkably, little is known about the structures of melanins, despite their abundance in the global biomass. This is due to the inability of current biochemi...

Among the Basidiomycetes the species of the genus Coprinus have black spores and hymenia that, at maturity, are transformed through autodigestion into a black or inky fluid that drops from the pileus and blackens the soil beneath the fruiting structures. The melanins from three different species of Coprinus have been characterized by spectroscopic techniques, including cross-polarization, magic...