Interaction of human substantia nigra neuromelanin with lipids and peptides

J Neurochem. 2000 Apr;74(4):1758-65. doi: 10.1046/j.1471-4159.2000.0741758.x.

Abstract

Neuromelanin was isolated from human substantia nigra using different procedures. In the pigment isolated by any of these procedures a peptide component covalently bound to the melanic structure was found, as shown by treatment with reagents known to eliminate noncovalently bound proteins. The amino acid content of such a peptide component was reproducible and corresponded to approximately 15% of the neuromelanin weight. Neuromelanin also showed the ability to absorb specifically lipid molecules, approximately 20% of its weight, and among these lipids cholesterol was identified, constituting approximately 5% of the total lipid mixture. A synthetic melanin, incubated with putamen homogenate, bound tissue peptides with an amino acid content quite close to that of neuromelanin. The same synthetic melanin adsorbed a lower amount of lipids from the putamen homogenate compared with neuromelanin. The sulfur content of neuromelanin was also reproducible even using different isolation procedures. A nonpigmented tissue like corpus callosum was used as a control and extracted by the method used for neuromelanin isolation; a total elimination of tissue components was found, thus demonstrating the capability of the reported procedures to isolate neuromelanin alone. The presence of a peptide component in the neuromelanin structure and the selective affinity for lipid molecules suggest new aspects of the functional role and metabolic pathway of neuromelanin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Amino Acids / metabolism
  • Corpus Callosum / chemistry
  • Corpus Callosum / metabolism
  • Endopeptidase K
  • Humans
  • Lipid Metabolism*
  • Magnetic Resonance Spectroscopy
  • Melanins / analysis
  • Melanins / metabolism*
  • Melanins / pharmacology
  • Middle Aged
  • Neuropeptides / metabolism*
  • Parkinson Disease / metabolism
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Protons
  • Substantia Nigra / chemistry
  • Substantia Nigra / metabolism*
  • Sulfur / analysis

Substances

  • Amino Acids
  • Melanins
  • Neuropeptides
  • Protons
  • neuromelanin
  • Sulfur
  • Endopeptidase K