CIS-TRANS ISOMERISM OF VASOACTIVE PEPTIDES IN THE LUNG

这项提案将调查一种潜在的监管机制 含脯氨酸的血管活性多肽的生理活性 残留物。在两个相互转化过程中存在着脯氨基-肽键 构型，即顺式和反式异构体。转化酶， 多肽酶和受体已被证明具有异构体偏好 体外研究中的多肽；例如，几种多肽酶 优先裂解Pro-肽键的反式异构体。 然而，很少有关于顺位和顺位的影响的研究。 脯氨酸肽键的反式异构体对酶的代谢或活性的影响 生物系统中的血管活性多肽。因此，拟议的研究 将检查肺多肽酶和受体对顺式和 含血管活性多肽的脯氨酸反式异构体的体外和体内研究 完整的灌流肺。 肺是这些研究的理想模型系统。它是最多的 已知的高效固定酶反应器，能够代谢 一次通过多种多肽的生理浓度 毛细管床。因为顺反异构化速度要慢得多 (几十秒到几百秒)单次通过的时间进程 通过肺(2至3秒)，肺的异构体特异性 在适当的条件下，多肽酶很容易显现。 肺多肽酶是否对顺式或反式异构体具有专一性 不同的血管活性多肽将从进程曲线中确定 多肽在肺内和体外的代谢。来自这些曲线的数据 将使用表示假设的数学模型来解释 动力学过程。多肽反式异构体的优先代谢 在肺中导致静脉流出物对顺式病毒高度浓缩 异构体。我们将利用这个生物反应器系统来研究 血管活性多肽激活受体的异构体偏好。 理解顺式和反式的功能作用的重要性 血管活性多肽中的脯氨基-肽键的异构体通过 最近发现的一个普遍存在的肽基-脯氨酰顺-反式家族 异构酶。这些酶，也是免疫亲和素结合的 免疫抑制药物环孢素A和FK506的蛋白质， 催化脯氨酸肽键的顺反异构化。在我们的 提案，我们将主要使用这些异构酶作为工具来研究 肺多肽酶和血管活性受体的异构体特异性 多肽。巧合的是，我们的结果也可能为 环孢素A心血管毒性机制的研究进展 免疫抑制与炎症、免疫亲和素活性可能 以这种方式折衷以改变正常的异构化动力学 血管活性物质。这可能会导致正常利率的失衡。 这些多肽的新陈代谢或激活。

This proposal will investigate a potential regulating mechanism of the physiological activity of vasoactive peptides that contain proline residues. Prolyl-peptide bonds exist in two interconverting configurations, i.e, as cis and trans isomers. Converting enzymes, peptidases and receptors have been shown to have isomeric preferences for peptides in in vitro studies; for example, several peptidases preferentially cleave trans isomers of prolyl-peptides bonds. Nevertheless, there have been few studies of the influence of cis and trans isomers of prolyl-peptide bonds on metabolism or activity of vasoactive peptides in biological systems. Therefore, the proposed study will examine the preferences of lung peptidases and receptors for cis and trans isomers of proline containing vasoactive peptides in vitro and in the intact perfused lung. The lung is an ideal model system for these studies. It is the most efficient fixed enzyme reactor known, capable of metabolizing physiological concentrations of many peptides in a single pass through the capillary bed. Since cis-trans isomerization is significantly slower (tens to hundreds of seconds) that the time course of a single pass through the lungs (two to three seconds), isomeric specificities of lung peptidases are readily apparent under the appropriate conditions. Whether lung peptidases are specific for cis or trans isomers of different vasoactive peptides will be determined from progress curves for peptide metabolism in the lung and in vitro. The data from theses curves will be interpreted using mathematical models that represent hypothesized kinetic processes. Preferential metabolism of trans isomers of peptides in the lung causes the venous effluent to be highly enriched for cis isomers. We will take advantage of this bioreactor system to study the isomeric preferences of receptor activation by vasoactive peptides. The importance of understanding the functional roles of cis and trans isomers of prolyl-peptide bonds in vasoactive peptides is highlighted by the recent discovery of a ubiquitous family of peptidyl-prolyl cis-trans isomerases. These enzymes, which are also the immunophilin binding proteins for the immunosuppressive drugs cyclosporine A and FK506, catalyze cis-trans isomerization of prolyl-peptide bonds. In our proposal, we will use these isomerases primarily as tools to study the isomeric specificities of lung peptidases and receptors for vasoactive peptides. Coincidently, our results may also provide insights into a mechanism of cardiovascular toxicity of cyclosporine A. In immunosuppression and inflammation, immunophilin activity may be compromised in such a way as to alter normal isomerization kinetics of vasoactive substances. This could lead to imbalances in the normal rates of metabolism or activation of these peptides.