NEUROPEPTIDES--APPROACHES TO ALPHA-AMIDATION EFFECTORS

神经肽，现在被认为是至关重要的参与许多中央和 已知外周功能是由较大的前体通过以下途径产生的： 各种翻译后的修饰。 特别地，羧基 末端α-酰胺化是生物学中的关键结构特征， 活性（可能在调节和对C-外肽酶的抗性中） 许多神经激素，与CA。50%的已知肽类激素 在其C-末端酰胺化。 尽管酶学和 酰胺化的生物化学已经进行了积极的研究， 时间，只有在过去两年中才变得清楚，酰胺化是 实际上是两步的过程。 肽酰甘氨酸α-酰胺化酶 单加氧酶（PAM）催化α-羟基甘氨酸的形成 甘氨酸延伸底物的衍生物。 我们的实验室最近 我们从垂体神经中间体中分离出一种新的酶， 命名为肽酰氨基乙醇酸裂解酶（PGL;见随附的信件记录 IUB酶命名委员会主席同意 这个名字）。 我们证明PGL催化第二步， α-羟基甘氨酸衍生物的神经肽酰胺化-脱烷基化 以产生最终的酰胺产物。 此外，我们的实验室还 证明了嗜铬颗粒中存在PAM和PGL， 我们已经开发出第一个小分子底物以及新的 对酶的灵敏测定。 鉴于人们逐渐认识到， α-酰胺化的关键神经化学作用，我们建议启动 一项新的研究计划专注于这一过程。 我们的目标是探索 神经肽酰胺化调节及其与 嗜铬细胞中的儿茶酚胺加工，以表征酰胺化 酶从各种来源，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.