CIS-TRANS ISOMERISM OF VASOACTIVE PEPTIDES IN THE LUNG

该提案将研究一种潜在的调节机制， 含脯氨酸的血管活性肽的生理活性 残基 脯氨酰-肽键存在于两个相互转化的 这些异构体具有不同的构型，即顺式和反式异构体。 转化酶， 肽酶和受体已经显示出对 肽在体外研究中;例如， 优先裂解脯氨酰-肽键的反式异构体。 然而，很少有研究的影响， 脯氨酰-肽键的反式异构体对代谢或活性的影响 生物系统中的血管活性肽。 因此，拟议的研究 将研究肺肽酶和受体对顺式和 含脯氨酸的血管活性肽的反式异构体的体外和体内研究 完整的灌注肺 肺是这些研究的理想模型系统。 它是最 已知的高效固定酶反应器，能够代谢 在单次通过中许多肽的生理浓度 毛细血管床 由于顺反异构化明显较慢， (tens到几百秒），单次通过的时间过程 通过肺部（两到三秒），肺部的异构特异性 肽酶在适当的条件下是显而易见的。 肺肽酶是否特异于顺式或反式异构体 不同的血管活性肽将从进展曲线确定， 在肺和体外的肽代谢。 这些曲线的数据 将使用数学模型来解释， 动力学过程 多肽反式异构体的优先代谢 导致静脉流出物高度富集顺式肾上腺素 异构体 我们将利用这个生物反应器系统来研究 血管活性肽对受体激活的异构体偏好。 理解顺式和反式的功能作用的重要性 血管活性肽中脯氨酰-肽键的异构体突出显示为 一个普遍存在肽基脯氨酰顺反结构家族的发现 异构酶 这些酶，也是亲免蛋白结合 免疫抑制药物环孢素A和FK 506的蛋白质， 催化脯氨酰-肽键的顺-反异构化。 在我们 建议，我们将使用这些异构酶主要作为工具来研究 肺血管活性肽酶和受体的异构特异性 缩氨酸 巧合的是，我们的研究结果也可以提供一个深入的了解， 环孢素A的心血管毒性机制 在 免疫抑制和炎症，亲免素活性可能 以这样的方式妥协，以改变正常的异构化动力学， 血管活性物质 这可能导致正常利率失衡 这些肽的代谢或激活。

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.