The Incorporation of Various Metal Ions into in Vivo- and in Vitro-Produced Melanin

Small amounts of a number of metal ions have been found in melanins obtained from natural sources, and ^{140}{\rm Ba}$ and 226 Ra have been found to deposit in tissues containing melanin. In the studies reported here, some aspects of the chemical nature of the incorporation were investigated with ra...

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Bibliographic Details
Published in:Radiation research 1967-09, Vol.32 (1), p.1-12
Main Authors: Bruenger, F. W., Stover, B. J., Atherton, D. R.
Format: Article
Language:English
Subjects:
Actinium - metabolism
Barium - metabolism
Cations
In Vitro Techniques
Melanin
Melanins - metabolism
Melanoma
Metal ions
Nuclides
Polymers
Proteins
Radioisotopes - metabolism
Radionuclides
Radium - metabolism
Space life sciences
Stover
Strontium
Strontium Isotopes - metabolism
Thorium - metabolism
Yttrium Isotopes - metabolism
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Summary:Small amounts of a number of metal ions have been found in melanins obtained from natural sources, and ^{140}{\rm Ba}$ and 226 Ra have been found to deposit in tissues containing melanin. In the studies reported here, some aspects of the chemical nature of the incorporation were investigated with radionuclides of high specific activity. The uptake of metal ions by synthetic melanin from a physiological buffer increased with decreasing hydrated ionic radius, decreased with decreasing pH, and decreased in the presence of chelating agents. Replacement of melanin-bound ${\rm Ra}^{++}$ with H+ demonstrated the reversibility of the reaction. Comparative studies with synthetic melanin and natural melanin plus its protein showed that the role of the protein in the reactions is small. Both the reaction characteristics and the chemical structures of melanin and of weak acid cation exchangers are similar, which suggests that metal ions and melanin interact by ion exchange.
ISSN:0033-7587
1938-5404
DOI:10.2307/3572300