NEUROPEPTIDES--APPROACHES TO ALPHA-AMIDATION EFFECTORS

神经肽，现在被认为是重要的参与许多中枢和 外周功能，已知是由较大的前体通过 各种翻译后修饰语。尤其是羧基 末端α-酰胺化是生物体的一个重要结构特征 活性(可能与对C-外肽酶的调节和抗性有关) 在许多神经激素中，约50%的已知多肽荷尔蒙是 在他们的C-终端上被胺化了。尽管无论是酶学还是 酰胺化的生物化学已经被积极地研究了一些 时间，只是在过去的两年里，人们才清楚地知道，酰胺化是 实际上是一个分两步走的过程。肽甘氨酸α-酰胺化酶 单加氧酶(PAM)催化生成α-羟基甘氨酸 甘氨酸延伸底物的衍生物。我们的实验室最近 从我们已有的神经中间垂体中分离出一种新的酶 命名为多肽片状乙醇酸裂解酶(PGL；见所附信函记录 IUB酶命名委员会主席同意 此名称)。我们证明了PGL催化第二步 神经肽酰胺化--α-羟基甘氨酸衍生物的脱烷基化 来生产最终的酰胺产品。此外，我们实验室还 证实嗜铬颗粒中同时存在PAM和PGL，以及 我们已经开发了第一批小分子底物以及新的 酶的灵敏化验。鉴于正在出现的认识到 α-酰胺化的关键神经化学作用，我们建议启动 一个专注于这一过程的新的研究计划。我们的目标是探索 神经肽酰胺化的调控及其与神经生长因子的关系 儿茶酚胺在嗜铬细胞中的处理，以表征胺化 来自各种来源的酶，并设计和表征新的类别 神经肽酰胺化的抑制剂和基于机制的效应物。

Neuropeptides, now recognized to be vitally involved in many central and peripheral functions, are known to be generated from larger precursors via a variety of postranslational modifications. In particular, carboxyl terminus alpha-amidation is a key structural feature in the biological activity (and probably in regulation and resistance toward C-exopeptidases) of many neurohormones, with ca. 50% of known peptide hormones being amidated at their C-terminii. Although both the enzymology and biochemistry of amidation have been under active investigation for some time, only within the last two years has it become clear that amidation is actually a two step process. The enzyme peptidylglycine alpha-amidating monooxygenase (PAM) catalyzes formation of the alpha-hydroxyglycine derivative of the glycine extended substrate. Our laboratory recently isolated a novel enzyme from neurointermediate pituitary which we have named peptidylamidoglycolate lyase (PGL; see attached letter documenting consent of the Chairman of the Enzyme Nomenclature Commission of the IUB to this name). We demonstrated that PGL catalyzes the second step in neuropeptide amidation -- dealkylation of alpha-hydroxyglycine derivatives to produce the final amide product. In addition, our laboratory has also demonstrated the presence of both PAM and PGL in chromaffin granules, and we have developed the first small molecule substrates as well as new sensitive assays for the enzymes. In view of the emerging recognition of the crucial neurochemical role of alpha-amidation, we propose to initiate a new research program focusing on this process. Our goals are to explore the regulation of neuropeptide amidation and its relationship to catecholamine processing in chromaffin cells, to characterize amidating enzymes from various sources, and to design and characterize novel classes of inhibitors and mechanism-based effectors for neuropeptide amidation.