PMID- 10913829
OWN - NLM
STAT- MEDLINE
DCOM- 20001103
LR  - 20190610
IS  - 0006-3002 (Print)
IS  - 0006-3002 (Linking)
VI  - 1475
IP  - 3
DP  - 2000 Jul 26
TI  - Isolation and characterization of mammalian eumelanins from hair and irides.
PG  - 295-306
AB  - A new enzymatic procedure was developed for isolation of eumelanin from black 
      human hair which might provide a substantially intact pigment for structural 
      characterization. Sequential digestion with protease, proteinase K and papaine in 
      the presence of dithiothreitol afforded a pigment with a 6% w/w protein content. 
      HPLC analysis of pyrrole acids resulting from alkaline H(2)O(2) degradation, 
      carboxyl content determination, and ferricyanide titration showed that the 
      isolated pigment is made up of 5,6-dihydroxyindole (DHI)- and 5, 
      6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units at a 6:1 ratio, 
      exhibiting a significant degree of oxidative degradation. For comparison, a 
      different eumelanin isolated from black bovine irides by a similar enzymatic 
      procedure was analyzed. Matrix-assisted laser desorption ionization (MALDI) mass 
      spectrometry of the final pigment provided evidence for homologous series of 
      DHICA oligomers, while chemical analysis allowed an estimate of 2:1 
      DHICA/DHI-derived units in the polymer, with a substantial proportion of intact 
      o-diphenolic functions. Iris melanin proved able to promote the Fenton oxidation 
      of deoxyribose while hair melanin was ineffective. Overall, these results 
      provide, for the first time, unambiguous evidence for marked structural 
      differences of mammalian eumelanins which may be directly related to the 
      diversity of the sites of biosynthesis and storage, as well as to functional role 
      of these pigments.
FAU - Novellino, L
AU  - Novellino L
AD  - Department of Organic and Biological Chemistry, University of Naples Federico II, 
      Via Mezzocannone 16, I-80134 Naples, Italy.
FAU - Napolitano, A
AU  - Napolitano A
FAU - Prota, G
AU  - Prota G
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Biochim Biophys Acta
JT  - Biochimica et biophysica acta
JID - 0217513
RN  - 0 (Ferricyanides)
RN  - 0 (Indoles)
RN  - 0 (Melanins)
RN  - 0 (Proteins)
RN  - 0 (Pyrroles)
RN  - 12627-86-0 (eumelanin)
RN  - 13408-62-3 (hexacyanoferrate III)
RN  - 142M471B3J (Carbon Dioxide)
RN  - 4790-08-3 (5,6-dihydroxy-2-indolylcarboxylic acid)
RN  - 533-67-5 (Deoxyribose)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - Z3OC8499KG (5,6-dihydroxyindole)
SB  - IM
MH  - Animals
MH  - Carbon Dioxide/analysis
MH  - Cattle
MH  - Deoxyribose/chemistry
MH  - Europe/ethnology
MH  - Ferricyanides
MH  - Hair/*chemistry
MH  - Humans
MH  - Hydrogen Peroxide
MH  - Hydrogen-Ion Concentration
MH  - Indoles/analysis
MH  - Iris/*chemistry
MH  - Melanins/*chemistry/*isolation & purification
MH  - Models, Molecular
MH  - Oxidation-Reduction
MH  - Proteins/analysis
MH  - Pyrroles/analysis
MH  - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
MH  - Spectrophotometry, Ultraviolet
EDAT- 2000/07/29 11:00
MHDA- 2001/02/28 10:01
CRDT- 2000/07/29 11:00
PHST- 2000/07/29 11:00 [pubmed]
PHST- 2001/02/28 10:01 [medline]
PHST- 2000/07/29 11:00 [entrez]
AID - S0304-4165(00)00080-5 [pii]
AID - 10.1016/s0304-4165(00)00080-5 [doi]
PST - ppublish
SO  - Biochim Biophys Acta. 2000 Jul 26;1475(3):295-306. doi: 
      10.1016/s0304-4165(00)00080-5.