Nakazawa M, Tsuchiya M, Hayasaka S, Mizuno K
Exp Eye Res. 1985 Aug;41(2):249-58. doi: 10.1016/0014-4835(85)90030-2.
Tyrosinase activity in crude extracts from various tissues of the adult bovine eye was examined biochemically. Enzyme activity was measured by using L-3,4-dihydroxyphenylalanine (L-DOPA) as substrate and determining colorimetrically by an increase in absorbancy at 400 or 475 nm. Tyrosinase activity was found in the ciliary body, iris, and choroid with the ciliary body having the highest enzyme activity. The enzyme was 1324-fold purified from the crude extract of the ciliary body by ammonium sulfate fractionation, trypsin digestion, followed by chromatography on Sephacryl S-200, hydroxylapatite, and DEAE-cellulose columns. The apparent Km value for L-DOPA was 0.2 mM and the molecular weight of the enzyme was estimated to be 70000 by gel method. The enzyme activity was markedly reduced by phenylthiourea and diethyldithiocarbamate, specific inhibitors of tyrosinase.
对成年牛眼各组织粗提物中的酪氨酸酶活性进行了生化检测。以L - 3,4 - 二羟基苯丙氨酸（L - DOPA）为底物，通过在400或475 nm处吸光度增加进行比色测定来测量酶活性。在睫状体、虹膜和脉络膜中发现了酪氨酸酶活性，其中睫状体的酶活性最高。通过硫酸铵分级沉淀、胰蛋白酶消化，然后在Sephacryl S - 200、羟基磷灰石和DEAE - 纤维素柱上进行层析，从睫状体粗提物中对该酶进行了1324倍的纯化。L - DOPA的表观Km值为0.2 mM，通过凝胶法估计该酶的分子量为70000。酪氨酸酶的特异性抑制剂苯基硫脲和二乙基二硫代氨基甲酸盐可显著降低该酶的活性。
