Partial Purification and Characterization of DOPA Quinone Imine Conversion Factor from Larval Hemolymph of the Silkworm, Bombyx mori

Yoichi Aso, Kohji Yamamoto, Takaaki Yoshinaga, Hikaru Yamamoto, Takeshi Yamagami

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DOPA quinone imine conversion factor was partially purified from larval hemolymph of the silkworm, Bombyx mori, using a novel assay. The factor was labile at 4°C below pH 5 and above pH 11, and at pH 8.5 above 55°C. Activity of the factor was maximal at pH 7.5–9. The factor catalyzed the decolorizations of L-DOPA methyl ester and α-methyl DOPA methyl ester chromes besides DOPA quinone imine. HPLC analysis indicated that the factor-catalyzed decolorization reaction of DOPA quinone imine resulted in the accumulation of dihydroxyindole. Based on spectral changes of α-methyl DOPA methyl ester chrome, it was suggested that the factor catalyzed the intramolecular oxidoreduction of DOPA quinone imine. During the oxidation of L-DOPA with endogenous phenoloxidase, the factor facilitated the formation of melanochrome.

Original languageEnglish
Pages (from-to)277-281
Number of pages5
JournalBioscience, biotechnology, and biochemistry
Issue number2
Publication statusPublished - Jan 1 1995


All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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