CHARACTERISTICS OF PHENOL OXIDASE OF SCHISTOSOMA-MANSONI AND ITS FUNCTIONAL IMPLICATIONS IN EGGSHELL SYNTHESIS
CHARACTERISTICS OF PHENOL OXIDASE OF SCHISTOSOMA-MANSONI AND ITS FUNCTIONAL IMPLICATIONS IN EGGSHELL SYNTHESIS
复制标题
DOI：
10.2307/3283563
复制
发表时间：
1993-06-01
影响因子：
1.3
通讯作者：
LOVERDE, PT
中科院分区：
文献类型：
--
作者：
ESHETE, F;LOVERDE, PT
有人建议，酚氧化酶的酶的寄生虫和其他吸虫有一个至关重要的作用，在交联的前体蛋白质的蛋壳的形成。然而，到目前为止，没有直接的证据表明，该酶催化的蛋壳前体蛋白的翻译后修饰所必需的反应。在这份报告中，我们证明，蛋壳前体蛋白作为底物的一个arrhosome馏分催化的2个步骤中的酪氨酸氧化，这种行动的酚氧化酶的蠕虫馏分导致酪氨酸依赖性的不溶解和聚集的蛋白质，这表明在翻译后修饰和交联的arrhosome蛋壳蛋白酶的作用。从曼氏血吸虫富含酶的馏分催化两个步骤的反应所需的酪氨酸残基的转换假定的蛋壳前体蛋白（p48）醌。寄生虫级分还催化游离L-酪氨酸羟基化为多巴（单酚氧化酶活性）和L-多巴氧化为多巴醌（二酚氧化酶活性）。这两种酶的活性都与膜结构紧密结合，对已知抑制功能相关酶酪氨酸酶的试剂敏感，并且可能存在于同一蛋白质上
It is proposed that the phenol oxidase enzyme of schistosomes and other trematodes has a crucial role in the cross-linking of precursor proteins in the formation of the eggshell. However, to date there is no direct evidence to show that the enzyme catalyzes the reactions necessary for the posttranslational modification of eggshell precursor proteins. In this report we demonstrate that an eggshell precursor protein acts as a substrate for a schistosome fraction that catalyzed the 2 steps in the oxidation of tyrosine, This action of the phenol oxidase-containing worm fraction resulted in the tyrosine-dependent insolubilization and aggregation of the protein, suggesting a role for the enzyme in the posttranslational modification and cross-linking of schistosome eggshell proteins. The enzyme-rich fraction from Schistosoma mansoni catalyzed both steps of the reactions necessary for the conversion of tyrosine residues on putative eggshell precursor protein (p48) to quinones. The parasite fraction also catalyzed the hydroxylation of free L-tyrosine to DOPA (monophenol oxidase activity) and the oxidation Of L-DOPA to dopaquinone (diphenol oxidase activity). Both activities of the enzyme are avidly bound to membranous structures, are susceptible to agents known to inhibit a functionally related enzyme, tyrosinase, and may reside on the same protein