Assays for mammalian tyrosinase: a comparative study.
Assays for mammalian tyrosinase: a comparative study.
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哺乳动物酪氨酸酶测定：比较研究。
DOI：
10.1111/j.1600-0749.1988.tb00128.x
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
J. Lozano
中科院分区：
文献类型：
--
作者：
J. R. Jara;F. Solano;J. Lozano
本文对目前应用最广泛的三种测定酪氨酸酶活性的方法进行了比较研究：两种以L酪氨酸为底物的放射测定法(酪氨酸羟基酶和黑色素形成活性)和一种以L-多巴为底物的分光光度法(多巴氧化酶活性)。这三种方法同时用于测定Harding-Passey小鼠黑色素瘤的可溶性、黑色素体和微粒体酪氨酸酶同工酶的活性。这项研究的目的是找出三种不同测定方法测得的酪氨酸酶活性之间的相关性，并确定这种相关性是否随同工酶及其纯化程度的不同而不同。结果表明，哺乳动物酪氨酸酶对L-多巴的转化率大于对L-酪氨酸的转化率。因此，在以L-多巴为底物的测定中，以每分钟转化底物的摩尔表示的酶活性高于以L-酪氨酸为底物的测定。此外，羟化的L酪氨酸转化为黑色素的百分比很低，受几个因素的影响，明显降低了黑色素形成试验所测得的酪氨酸酶活性。考虑到这些因素，提出了平均测定间因子。它们的值是10，将黑色素形成转换为酪氨酸羟基酶活性，100，将酪氨酸羟基酶转换为多巴氧化酶活性，以及1,000，将黑色素形成转换为多巴氧化酶活性。这些数值的变化是由于酪氨酸酶制剂中存在独立于酪氨酸酶的黑素合成的抑制剂或调节因子而引起的。
This work describes a comparative study of the tyrosinase activity determined using three methods which are the most extensively employed; two radiometric assays using L-tyrosine as substrate (tyrosine hydroxylase and melanin formation activities) and one spectrophotometric assay using L-dopa (dopa oxidase activity). The three methods were simultaneously employed to measure the activities of the soluble, melanosomal, and microsomal tyrosinase isozymes from Harding-Passey mouse melanoma through their purification processes. The aim of this study was to find any correlation among the tyrosinase activities measured by the three different assays and to determine whether that correlation varied with the isozyme and its degree of purification. The results show that mammalian tyrosinase has a greater turnover number for L-dopa than for L-tyrosine. Thus, enzyme activity, expressed as mumol of substrate transformed per min, is higher in assays using L-dopa as substrate than those using L-tyrosine. Moreover, the percentage of hydroxylated L-tyrosine that is converted into melanin is low and is affected by several factors, apparently decreasing the tyrosinase activity measured by the melanin formation assay. Bearing these considerations in mind, average interassay factors are proposed. Their values are 10 to transform melanin formation into tyrosine hydroxylase activity, 100 to transform tyrosine hydroxylase into dopa oxidase activity, and 1,000 to transform melanin formation into dopa oxidase activity. Variations in these values due to the presence in the tyrosinase preparations of either inhibitors or regulatory factors in melanogenesis independent of tyrosinase are also discussed.
影响因子：
56.9
作者：
KORNER, A;PAWELEK, J
通讯作者：
PAWELEK, J
通过高效液相色谱法测量人毛球中的多巴氧化酶活性。
DOI：
10.1111/1523-1747.ep12355192
发表时间：
1986
期刊：
The Journal of investigative dermatology
影响因子：
--
作者：
Townsend,DW;Olds,DP;King,RA
通讯作者：
King,RA
哺乳动物酪氨酸酶（多羟基苯基氧化酶）的优化测定。
影响因子：
2.9
作者：
Townsend,D;Guillery,P;King,RA
通讯作者：
King,RA