Abstract
Two membrane bound enzymes which tautomerize L-dopachrome and are specific for the L-isomer of dopachrome have been defined in melanin forming cells. Another enzyme that tautomerizes D-dopachrome with concomitant decarboxylation to give 5,6-dihydroxyindole (DHI) was found in the cytoplasm of human melanoma cells, human liver and in all of the organs studied in rat. The decolorization of D-dopachrome with the formation of DHI was used in monitoring the isolation of a tautomerase from liver of male rats and therefore the enzyme is provisionally called D-dopachrome tautomerase. The molecular weight of D-dopachrome tautomerase monomer was approximately 12 kD and its N-terminal amino acid sequence was P-F-V-E-L-E-T-N-L-P-A-. The Km for D-dopachrome was 1.5 mM and Vmax 0.5 mmol per min and mg protein.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Brain / enzymology
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Chromatography, Gel
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Chromatography, High Pressure Liquid
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Electrophoresis, Polyacrylamide Gel
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Humans
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Indolequinones*
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Indoles / analysis
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Indoles / metabolism*
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Intramolecular Oxidoreductases*
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Isomerases / chemistry
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Isomerases / isolation & purification*
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Isomerases / metabolism*
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Kidney / enzymology
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Kinetics
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Liver / enzymology*
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Male
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Melanoma
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Molecular Sequence Data
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Molecular Weight
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Myocardium / enzymology
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Peptide Fragments / chemistry
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Quinones / metabolism*
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Rats
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Rats, Sprague-Dawley
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Sequence Homology, Amino Acid
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Spleen / enzymology
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Tumor Cells, Cultured
Substances
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Indolequinones
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Indoles
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Peptide Fragments
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Quinones
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dopachrome
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Isomerases
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Intramolecular Oxidoreductases
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dopachrome isomerase
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5,6-dihydroxyindole