BIOSYNTHESIS OF CATECHOLAMINES

我们实验室以前的研究表明，四氢生物蝶呤 (BH4)在体外激活一种氨基羟基酶磷酸酶。现在 结果与这些早期的发现一致，并表明BH4具有 在完整的大鼠纹状体突触体内也有类似的效果。增加了…… 由摄入外源性蝶呤引起的突触体内BH4产生 正常人酪氨酸羟化酶去磷酸化水平的增加 突触体。起效迅速，且呈浓度依赖性。此外， 这一反应似乎是针对BH4的。一种类似且可逆的 使用BH4前体Sepiapterin观察到了效果，而生物蝶呤 实际上是不活跃的。未来的研究将继续探讨这部小说 监管职能，以期进一步说明 BH4在体内的作用及其生物学意义。 其他研究已经使用大鼠纹状体切片来检测酪氨酸的作用 在高苯丙氨酸血症状态下大脑中的羟基酶。具体来说， 内源性蛋白质结合酪氨酸的相对贡献 比较了由外源~3H-苯丙氨酸生成~3H-酪氨酸与 来自外源的14C-酪氨酸。新形成的~3H-酪氨酸参入细胞 证明了蛋白质的存在。这种~3H-酪氨酸的掺入依赖于 外源~3H-苯丙氨酸的浓度。

Previous studies in our laboratory have shown that tetrahydrobiopterin (BH4) activates a sine hydroxylase phosphatase in vitro. The present results,are consistent with these earlier findings and suggest that BH4 has a similar effect in intact rat striatal synaptosomes. An increase in intrasynaptosomal BH4, caused by the intake of exogenous pterin, produced an increase in the dephosphorylation of tyrosine hydroxylase in intact synaptosomes. The effect was rapid and concentration dependent. Moreover, the response appeared to be specific for BH4. A similar and reversible effect was observed with the BH4 precursor sepiapterin, whereas biopterin was virtually inactive. Future studies will continue to address this novel regulatory function with a view to characterizing further the mode of action of BH4 and its biological significance in vivo. Other studies have used rat striatal slices to examine the role of tyrosine hydroxylase in the brain during hyperphenylalanemic states. Specifically, the relative contribution to the protein-bound tyrosine of endogenously formed 3H-tyrosine from exogenous 3H-phenylalanine was compared to that from exogenous l4C-tyrosine. Newly formed 3H-tyrosine incorporation into protein was demonstrated. This 3H-tyrosine incorporation was dependent on the concentration of exogenous 3H-phenylalanine.