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M R Chedekel

Publications and source records attributed to M R Chedekel.

25 records · Page 2Linked to original sources
PubMed1980

Mutagenicity of melanin from human red hair.

The Salmonella typhimurium histidine reversion test of Ames et al. was used to demonstrate the pheomelanin, the red-brown polymeric pigment produced in human skin and hair, becomes mutagenic after exposure to long wave-length UV-light; a finding consistent with the UV-induced somatic mutation hypothesis for the origin of freckles and the high susceptibility of redheads and blonds to sunlight-induced skin cancers.

Hair↗
PubMed1978

Photodestruction of pheomelanin: role of oxygen.

Pheomelanin, the red-brown polymeric pigment in the skin and hair of red-headed humans, is composed of a protein fraction covalently bound to a colored chromophore. Photolysis of aerated aqueous phemelanin solutions, isolated from human red hair, results in destruction of the chromophore and liberation of the peptide fraction. The rate of photolysis depends on the pH and the concentration of both pigment and oxygen and is slightly inhibited by the enzyme superoxide dismutase (superoxide:superoxide oxidoreductase EC 1.15.1.1). Pheomelanin photolyzed in the presence of nitroblue tetrazolium results in the formation of a blue diformazan, whether or not oxygen is present. Superoxide dismutase inhibits the aerobic photoreduction of nitroblue tetrazolium whereas, in the absence of oxygen, no inhibition is observed. These experiments strongly suggest the involvement of superoxide in the aerobic photolysis of pheomelanin and point out a possible mechanism for ultraviolet-induced cell damage in redheads.

Amino Acids↗