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Tyrosinase activity in human ocular malignant melanoma

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Abstract

We examined tyrosinase activity in pigmented specimens from three cases of ocular malignant melanoma. Tissue (cholate-trypsin-treated) extract was prepared in cholate-phosphate buffer by homogenization, centrifugation, trypsin digestion, and hydroxylapatite column chromatography. Tyrosinase activity was spectrophotometrically assayed as dopa (L-3,4-dihydroxylphenylalanine) oxidase activity. Tyrosinase activity was detected in the cholate-trypsin-treated extracts. Enzyme activity was inhibited by phenylthiourea but not by 3-iodo-tyrosine. The enzyme was inactivated when extract was preheated or digested with pronase. We believe that our findings confirm the presence of tyrosinase activity in ocular malignant melanoma.

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Authors and Affiliations

  1. Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan

    S. Hayasaka, M. Nakazawa, S. Ishiguro & K. Mizuno

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  1. S. Hayasaka
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  2. M. Nakazawa
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  3. S. Ishiguro
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  4. K. Mizuno
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Hayasaka, S., Nakazawa, M., Ishiguro, S. et al. Tyrosinase activity in human ocular malignant melanoma. Graefe's Arch Clin Exp Ophthalmol 224, 310–312 (1986). https://doi.org/10.1007/BF02143076

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  • DOI: https://doi.org/10.1007/BF02143076

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