NOREPINEPHRINE BIOSYNTHESIS--ROLE OF ASCORBATE

中枢和海马的儿茶酚胺类神经递质和神经肽 外周神经激素系统可能与临床疾病有关 例如高血压、心脏异常和神经功能障碍 比如精神分裂症和其他精神疾病。因此 了解体内的儿茶酚胺神经递质， 神经肽激素在分子水平上的生物合成将是重要的 为了了解这些疾病的病因， 开发有效的治疗药物。抗坏血酸的作用 (Asc)在儿茶酚胺神经递质的生物合成中， 神经肽激素，因此，在整个神经内分泌功能， 得到了很好的认可。由于大量的神经内分泌囊泡 肾上腺髓质或其他内分泌腺不将Asc转移到 囊泡膜，跨膜血红素蛋白，细胞色素b561， 建议负责转移必要的减少 儿茶酚胺生物合成酶，多巴胺β- 单加氧酶（DbM）和神经肽加工末端酶， 肽基α-羟基化单加氧酶（PHM），来自胞质池 的ASC。虽然，最近的努力已经指向 理解这种复杂的电子转移过程在分子 水平，与儿茶酚胺和神经肽的生物合成， 这些努力的进展受到复杂性和 细胞内和细胞外因子作用的多样性。整体 我们计划的目标是确定的分子机制， 还原当量从胞质Asc转移到 神经内分泌颗粒通过仔细检查氧化还原 各种蛋白质在通路中的相互作用。我们建议 通过检查还原剂的相互作用来实现该目的， 阴离子酶激活剂，和其他底物与DbM，特别是在 与活性位点铜氧化还原中心的关系，使用各种合成 探针和光谱技术，并扩展类似的研究PHM。 与此同时，我们将纯化并进一步表征新鉴定的 酸性库珀蛋白作为细胞色素b561和DbM之间的氧化还原介体 (and PHM）。我们将研究单向的分子机制， 电子通过b561穿过颗粒膜的传递， 生物化学和生物物理技术。最后所有的信息将 结合起来，提出一个分子模型，在体内减少这两个 DbM和PHM。

The catecholamine neurotransmitters and neuropeptides in the central and peripheral neurohormonal system may be implicated in clinical disorders such as hypertension, cardiac abnormalities and neurological dysfunctions like schizophrenia and other mental illnesses. Therefore, the understanding of the in vivo catecholamine neurotransmitter and neuropeptide hormone biosynthesis at the molecular level will be important for the understanding of the etiology of these diseases and eventual development of effective therapeutic agents. The role of ascorbic acid (Asc) in the biosynthesis of both catecholamine neurotransmitters and neuropeptide hormones and thus, in overall neuroendocrine functions has been well recognized. Since numerous neuroendocrine secretory vesicles of the adrenal medullae or other endocrine glands do not transfer Asc across the vesicle membrane, the transmembrane hemoprotein, cytochrome b561, is proposed to be responsible for transferring the necessary reducing equivalents for both the catecholamine biosynthetic enzyme, dopamine beta- monooxygenase (DbM), and the neuropeptide processing terminal enzyme, peptidyl alpha-hydroxylating monooxygenase (PHM), from the cytosolic pool of Asc. Although, recent efforts have been directed towards the understanding of this intricate electron transfer process at the molecular level, in relation to catecholamine and neuropeptide biosynthesis, progress of these efforts has been hampered by the complexity and the diversity of the effects of intra-and extra-cellular factors. The overall objective of our program is to define the molecular mechanism of the transfer of reducing equivalents from the cytosolic Asc to the interior of the neuroendocrine granule by careful examination of the redox interactions of various proteins in the pathway. We are proposing to achieve this objective by examining the interaction of the reductant, anion enzyme activators, and other substrates with DbM especially in relation to the active site copper redox centers using various synthetic probes and spectroscopic techniques and to extend similar studies to PHM. In parallel, we will purify and further characterize the newly identified acidic cooper protein as a redox mediator between cytochrome b561 and DbM (and PHM). We will examine the molecular mechanism of the unidirectional electron transport across the granule membrane through b561 using biochemical and biophysical techniques. Finally all the information will be combined to propose a molecular model for the in vivo reduction of both DbM and PHM.