Comparison of the structural and physical properties of human hair eumelanin following enzymatic or acid/base extraction

Yan Liu, Valerie R. Kempf, J. Brian Nofsinger, Emily E. Weinert, Mark Rudnicki, Kazumasa Wakamatsu, Shosuke Ito, John D. Simon

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Eumelanin was isolated from a sample of black, Indonesian human hair using three different published procedures: two different acid/base extractions and an enzymatic extraction. The morphology and spectroscopic properties of the isolated pigments differ significantly. The acid/base procedures both yield an amorphous material, while enzymatic extraction yields ellipsoidal melanosomes. Amino acid analysis shows that there is protein associated with the isolated pigments, accounting for 52, 40 and 14% of the total mass for the two acid/base extractions and the enzymatic extraction, respectively. The amino acid compositions do not correlate with those of keratin or tyrosinase. Metal elemental analysis shows that the acid/base extraction removes a majority of many metal ions bound to the pigment. Chemical degradation analysis by KMnO4/H+ and H2O2/OH- indicates significant differences between the pigments isolated by acid/base and enzymatic extraction. After correction for the protein mass in the two pigments, the lower yields of both pyrrole-2,3,5-tricarboxylic acid and pyrrole-2,3-dicarboxylic acid, eumelanin degradation products, indicate acid/base extraction modifies the chemical structure of the melanin, consistent with the result of Soluene solubilizatior assay. While the optical absorption spectra of the bulk pigments are similar, the spectra of the molecular weight less than 1000 mass fractions differ significantly. The data clearly indicate that pigment obtained from human hair by acid/base extraction contains significant protein, exhibits destruction of the melanosome, and possesses altered molecular structure. The acid/base extracted hair melanin is not representative of the natural material and is a poor model system for studying the physical and biological properties of melanins. The enzymatically extracted hair melanin, on the contrary, retains the morphology of intact melanosomes and is an excellent source of human melanin.

Original languageEnglish
Pages (from-to)355-365
Number of pages11
JournalPigment Cell Research
Volume16
Issue number4
DOIs
Publication statusPublished - Aug 2003

Fingerprint

eumelanin
Hair
hairs
Structural properties
physical properties
Physical properties
Pigments
Melanins
Acids
melanin
pigments
acids
Melanosomes
pyrroles
chemical structure
Metals
tricarboxylic acids
Amino Acids
Proteins
Monophenol Monooxygenase

Keywords

  • 5,6-dihydroxyindole-2-carboxylic acid
  • 5,6-dihyroxyindole
  • Chemical analysis
  • Eumelanin structure
  • ICP-MS analysis
  • Melanin isolation
  • Optical spectroscopy
  • Scanning microscopy

ASJC Scopus subject areas

  • Cell Biology
  • Agronomy and Crop Science
  • Plant Science
  • Clinical Biochemistry
  • Developmental Biology

Cite this

Comparison of the structural and physical properties of human hair eumelanin following enzymatic or acid/base extraction. / Liu, Yan; Kempf, Valerie R.; Nofsinger, J. Brian; Weinert, Emily E.; Rudnicki, Mark; Wakamatsu, Kazumasa; Ito, Shosuke; Simon, John D.

In: Pigment Cell Research, Vol. 16, No. 4, 08.2003, p. 355-365.

Research output: Contribution to journalArticle

Liu, Yan ; Kempf, Valerie R. ; Nofsinger, J. Brian ; Weinert, Emily E. ; Rudnicki, Mark ; Wakamatsu, Kazumasa ; Ito, Shosuke ; Simon, John D. / Comparison of the structural and physical properties of human hair eumelanin following enzymatic or acid/base extraction. In: Pigment Cell Research. 2003 ; Vol. 16, No. 4. pp. 355-365.
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abstract = "Eumelanin was isolated from a sample of black, Indonesian human hair using three different published procedures: two different acid/base extractions and an enzymatic extraction. The morphology and spectroscopic properties of the isolated pigments differ significantly. The acid/base procedures both yield an amorphous material, while enzymatic extraction yields ellipsoidal melanosomes. Amino acid analysis shows that there is protein associated with the isolated pigments, accounting for 52, 40 and 14{\%} of the total mass for the two acid/base extractions and the enzymatic extraction, respectively. The amino acid compositions do not correlate with those of keratin or tyrosinase. Metal elemental analysis shows that the acid/base extraction removes a majority of many metal ions bound to the pigment. Chemical degradation analysis by KMnO4/H+ and H2O2/OH- indicates significant differences between the pigments isolated by acid/base and enzymatic extraction. After correction for the protein mass in the two pigments, the lower yields of both pyrrole-2,3,5-tricarboxylic acid and pyrrole-2,3-dicarboxylic acid, eumelanin degradation products, indicate acid/base extraction modifies the chemical structure of the melanin, consistent with the result of Soluene solubilizatior assay. While the optical absorption spectra of the bulk pigments are similar, the spectra of the molecular weight less than 1000 mass fractions differ significantly. The data clearly indicate that pigment obtained from human hair by acid/base extraction contains significant protein, exhibits destruction of the melanosome, and possesses altered molecular structure. The acid/base extracted hair melanin is not representative of the natural material and is a poor model system for studying the physical and biological properties of melanins. The enzymatically extracted hair melanin, on the contrary, retains the morphology of intact melanosomes and is an excellent source of human melanin.",
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AU - Weinert, Emily E.

AU - Rudnicki, Mark

AU - Wakamatsu, Kazumasa

AU - Ito, Shosuke

AU - Simon, John D.

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