4-Hydroxyphenylpyruvate Dioxygenase and Tyrosinemia

描述（由申请人提供）：铁依赖性非血红素加氧酶是 这项研究的具体重点。这些酶催化重要的代谢， 在哺乳动物的新陈代谢过程中发生的分解代谢反应。最初的意图是 发展这些酶的化学的基本理解， 识别在过程中产生的瞬时氧中间体， 催化作用长期目标是找到证据， 用于特定催化步骤的过渡态， 状态模拟物可被开发为抑制性治疗剂以控制 通过关键的代谢途径。最初，酶 4-选择羟苯丙酮酸双加氧酶（HPPD）进行研究。 这种酶的许多催化功能的其他FII依赖 非血红素双加氧酶如芳香族加氧、氧化脱羧 和取代基迁移。此外，它是为数不多的α-酮之一， 晶体结构已知的酸依赖性加氧酶。此外，委员会认为， 它已经成为一个范例， 通过选择性酶抑制来治疗疾病。 1型酪氨酸血症是由缺乏活性延胡索酰乙酰乙酸酶引起的， 催化催化代谢途径中的最后一步的酶 酪氨酸。在没有治疗的情况下，这种疾病往往是致命的， 生命的第一年，总是在前二十年结束之前。是 然而，已知的是，抑制HPro催化第二步， 在大多数情况下，该途径是1型酪氨酸血症的有效治疗。 这项研究的部分目的是，这种抑制的机制， 在酶的催化事件的上下文中理解。实验 一种方法是将联合收割机稳态和预稳态分析与 选择性使用底物类似物、同位素标记和诱变， 晶体学以速率常数为基础检验机理假说 调制和结构。

DESCRIPTION (provided by applicant): Iron-dependent non-heme oxygenases are the specific focus of this research. These enzymes catalyze vital metabolic and catabolic reactions throughout mammalian metabolism. The initial intent is to develop a fundamental understanding of the chemistry of these enzymes by the identification of the transient oxygen intermediates that are generated during catalysis. The long-term objective is to find evidence for the geometry of transition states for specific catalytic steps such that stable transition state mimics can be developed as inhibitory therapeutic agents to control the flux through key metabolic pathways. Initially, the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) has been selected for investigation. This enzyme exemplifies many of the catalytic functions of other FeII-dependent non-heme dioxygenases such as aromatic oxygenation, oxidative decarboxylation and substituent migration. Furthermore, it is one of the few alpha-keto acid-dependent oxygenases for which the crystal structure is known. Moreover, it has become a paradigm example of the ability to alleviate metabolic disorders through selective enzymatic inhibition. Type 1 Tyrosinemia, is caused by a deficiency of active fumarylacetoacetase, an enzyme that catalyzes the final step in the pathway for the catabolism of tyrosine. In the absence of treatment this disease is often fatal in the first year of life and always prior the completion of the first two decades. It is known, however, that the inhibition of HPPD which catalyzes the second step of this pathway is, in most cases, an effective treatment for type 1 Tyrosinemia. Part of the intent of this research is that the mechanism of this inhibition be understood in the context of catalytic events of the enzyme. The experimental approach will be to combine steady state and pre-steady state analyses with the selective use of substrate analogs, isotopic labels and mutagenesis and crystallography to test mechanistic hypotheses on the basis of rate constant modulation and structure.