Comparison of Structural and Chemical Properties of Human Black-Hair and Red-Hair Melanosomes

Abstract

Melanosomes in black and red human hair are isolated and characterized by various chemical and physical techniques. Different yields of 4-amino-hydroxyphenolanaline by HI hydrolysis (a marker for pheomelanin) and pyrrole-2,3,5tricarboxylic acid by KMn04/H+ oxidation (a marker for eumelanin) indicate that the melanosomes in black hair are eumelanosomes, whereas those in red hair are mainly pheomelanosomes. Atomic force microscopy reveals that eumelanosomes and pheomelanosomes have ellipsoidal and spherical shapes, respectively. Eumelanosomes maintain structural integrity upon extraction from the keratin matrix, whereas pheomelanosomes tend to fall apart. The black-hair eumelanosomes have an average of 14.6 zk 0.5% amino acids content, which is attributed to the internal proteins entrapped in the melanosomes granules. The red-hair melanosomes contain more than 44% of amino acid content even after extensive proteolytic digestion. This high content of amino acids and the poorly reserved integrity of red-hair melanosomes suggest that some proteins are possibly covalently bonded with the melanin constituents in addition to those that are entrapped inside the melanin species. Soluene solubilization assay indicates the absorbance of melanin per gram of sample, adjusted for the amino acid content, is a factor of 2.9 greater for the black-hair melanosomes than the red-hair melanosomes. Metal analysis reveals significant amounts of diverse heavy metal ions bound to the two types of melanosomes. The amount of Cu(I1) and Zn(I1) are similar but Fe(II1) content is four times higher in the red-hair melanosomes. 13C solid-state nuclear magnetic resonance spectra and infrared spectra are presented and are shown to be powerful techniques qPosted on the website on 25 October 2004. -8655/05 for discerning differences in the amino acid contents, the 5,6dihydroxyindole-2-carboxylic acid:5,6-dihydroxyindole ratio, and the degree of cross-linking in the pigment. Excellent agreement is observed between these spectral results and the chemical degradation data.135

Direct chemical evidence for eumelanin pigment from the Jurassic period

“…The elemental analysis-C, H, and N-of the fossil melanin, fossil sediment, background standards for hydroxyapatite and calcium carbonate, and modern melanin specimens was performed at the Center for Organic Elemental Microanalysis at Kyoto University using combustion. From these data, the C, H and N ratio of the fossil melanin and organic content of the sediment could be determined (41). The results are given in Table S4.…”

Preparation of water-soluble melanin from squid ink using ultrasound-assisted degradation and its anti-oxidant activity

“…4. The absorption peaks were assigned according to the previously report on neuromelanin, darkhair melanin and synthetic melanin (Stainsack et al 2003;Liu et al 2005;Centeno and Shamir 2008). All the three fractions showed similar spectra as the original melanin with characteristic absorption peak at follows: 3300-3400 cm −1 for -OH stretching (−3400 cm −1 ) and -NH (−3300 cm −1 ) in indole or pyrrole; 2850-2920 cm −1 for stretching vibration of aliphatic C-H groups from amino acid; 1610-1690 cm −1 , the aromatic ring C=C, C=N bending and C=O stretching (non-carboxylic acid group); 1580 cm −1 for the ionization of the COO-and C=O; 1457 cm −1 for -CH 2 CH 3 bending; 1410 cm −1 for pyrrole ring stretching; 1360-1380 cm −1 , C-N stretching from amino acids and 1050-1100 cm −1 , alcoholic O-H from amino acids.…”

Modifying skin pigmentation – approaches through intrinsic biochemistry and exogenous agents

“…Tyrosinase (TYR) catalyzes the initial rate-limiting step in melanogenesis, the hydroxylation of tyrosine to β-3,4-dihydroxyphenylalanine (DOPA) and the subsequent oxidation of DOPA to DOPAquinone. In the presence of cysteine, DOPAquinone is converted stochiometrically into 3-or 5-cysteinylDOPA which oxidizes and polymerizes to pheomelanins [11,12]. After depletion of cysteine, DOPAquinone spontaneously cyclizes to form DOPAchrome.…”