Regulation of Phenylalanine Catabolism

描述（由申请方提供）：肝酶苯丙氨酸羟化酶负责催化饮食中过量的苯丙氨酸。酶水平的缺陷导致代谢紊乱苯丙酮尿症，如果不治疗，这种疾病具有破坏性的神经后果，证明了酶的生理重要性。苯丙氨酸羟化酶正常功能的核心是通过其底物苯丙氨酸和四氢生物蝶呤以及磷酸化来调节酶。这两种形式的调节都需要N端~117个残基的调节结构域。在普遍接受的调节模型中，酶的静息形式是无活性的，并且在调节位点处苯丙氨酸的变构结合将酶转化为活性形式。四氢生物蝶呤稳定非活性形式，而磷酸化增强转化为活性形式。本文提出的研究目标是了解变构调节的结构和动力学基础。拟议的实验将结合联合收割机现代结构方法（例如，NMR和质谱），并测量结合和催化的固有速率常数，以便更完整地了解苯丙氨酸羟化酶的变构调节。 公共卫生相关性：这是一项研究肝酶苯丙氨酸羟化酶调节的提案。这种酶的遗传缺陷，除非受影响的个体从出生起就被限制饮食。更好地理解这一调控将提高我们开发更好的PKU治疗方法的能力。

DESCRIPTION (provided by applicant): The liver enzyme phenylalanine hydroxylase is responsible for catabolism of excess phenylalanine in the diet. Deficiencies in levels of the enzyme result in the metabolic disorder phenylketonuria, a disease with devastating neurological consequences if untreated, demonstrating the physiological importance of the enzyme. Central to the proper function of phenylalanine hydroxylase is the regulation of the enzyme by its substrates, phenylalanine and tetrahydrobiopterin, and by phosphorylation. Both forms of regulation require the N-terminal ~117 residue regulatory domain. In the generally-accepted model for regulation, the resting form of the enzyme is inactive and allosteric binding of phenylalanine at a regulatory site converts the enzyme to an active form. Tetrahydrobiopterin stabilizes the inactive form, while phosphorylation potentiates the conversion to the active form. The goal of the research proposed here is to understand the structural and dynamic basis for the allosteric regulation. The proposed experiments will combine modern structural approaches (e.g., NMR and mass spectroscopy) with measurement of intrinsic rate constants for binding and catalysis in order to provide a more complete understanding of the allosteric regulation of phenylalanine hydroxylase. PUBLIC HEALTH RELEVANCE: This is a proposal to study the regulation of the liver enzyme phenylalanine hydroxylase. An inherited deficiency in this enzyme unless the affected individual is placed on a restricted diet from birth. A better understanding of the regulation will improve our ability to develop better treatments for PKU.