Mechanistic studies of Tyrosine Hydroxylase

酪氨酸羟化酶，一种含铁的蝶呤依赖性 单加氧酶催化的速率控制步骤， 儿茶酚胺类神经递质的生物合成 酪氨酸羟基化形成二羟基苯丙氨酸。 的 蝶呤依赖性单加氧酶是一个了解较少的组 酶。 这项研究的主要目的是了解 酪氨酸羟化酶的催化机理。 的dna 大鼠PC 12酪氨酸羟化酶已被克隆， 在高效杆状病毒表达系统中表达， 为了获得足够的纯材料， 问题研究 动力学机制将使用稳态 状态动力学和同位素捕获。 快速反应技术 将用于测量催化剂的形成速率， 中间体的 几种非生理氨基酸似乎 作为酪氨酸羟化酶的底物;这些反应 将进行研究，以获得有关身份的信息， 氧化物种。 这类酶，单加氧酶，催化一些 生物化学中最困难的反应。 因此它们 已经成为大量研究的对象。 机制 与此相反， 酪氨酸羟化酶。 它显示了一些重要的 差异;苯丙氨酸似乎不是底物 对于酪氨酸羟化酶，尽管数据不一致; 静息酶的氧化还原状态不同;酪氨酸 羟化酶可以使用H2O2代替四氢蝶呤。 这 这项研究还可以提供有关该机制的基本见解 其他类型的单加氧酶，因为它具有功能， 常见于黄素蛋白羟化酶和Fe（11） 单加氧酶

Tyrosine hydroxylase, an iron-containing, pterin-dependent monoxygenase catalyze the rate-controlling step in the biosynthesis of catecholamine neurotransmitters, the hydroxlation of tyrosine to form dihydroxyphenylalanine. The pterin-dependent monooxygenases are a poorly understood group of enzymes. The primary goal of this research is to understand the catalytic mechanism of tyrosine hydroxylase. The DNA for rat PC 12 tyrosine hydroxylase has been cloned and will be expressed in a high efficiency baculovirus expression system in order to obtain enough pure material for detailed mechanistic studies. The kinetic mechanism will be determined using steady state kinetics and isotope trapping. Rapid reaction techniques will be used to measure the rates of formation of catalytic intermediates. Several nonphysiological amino acids appear to act as substrates for tyrosine hydroxylase; these reactions will be studies to gain information about the identity of the oxygenating species. This class of enzymes, the monooxygenases, catalyze some of the most difficult reactions in biochemistry. Consequently, they have been the objects of a great deal of study. The mechanism of phenylalanine hydroxylase has been well studied in contrast to tyrosine hydroxylase. It shows a number of significant differences; phenylalanine does not appear to be a substrate for tyrosine hydroxylase although the data is not consistent; the redox state of the resting enzymes are different; tyrosine hydroxylase can use H2 02 in place of tetrahydropterins. This study could also offer fundamental insights into the mechanism of other classes of monooxygenases since it has features in common with both flavoprotein hydroxylases and Fe(11) monooxygenases.