MOLECULAR MODELING OF HUMAN CYTOCHROME P450C17 & P450C21

人细胞色素 P450C17 的分子建模

• 批准号: 6280124
• 负责人: RICHARD J. AUCHUS
• 金额: $ 0.91万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6280124
• 关键词: aging; biomedical resource; child (0-11); endocrine gland /system; female; growth /development; hormones; human subject; male; mother /infant health care; neoplasm /cancer; reproductive system

Cytochrome P450c17 catalyzes both the 17-hydroxylation and oxidative cleavage of C21 steroids in both human adrenal glands and gonads. Whereas adrenal 17-hydroxylase activity remains fairly constant after birth, adrenal lyase activity, reflected by serum dehydroepiandrosterone sulfate, rises during adrenarche at about age 8 and then declines progressively after age 50. Determining the three-dimensional structure of P450c17 would greatly enhance our understanding of how these two funamentally distinct activities of a single protein can be independently regulated. P450c21 is a related steroidogenic enzyme that catalyzes the 21-hydroxylase reaction. P450c17 and P450c21 have high sequence similarity and identical gene structures, and both utilize the same substrates (pregnenolone, progesterone, and their 17-hydroxy derivatives). The subtle differences in their substrate selectivities and catalytic specificities, however, lead to the production of different steroid hormones with vastly different biological activities. We believe that structure-function comparisons of the two enzymes will yield important insight to the actions of steroidogenic enzymes and approaches to their selective inhibition. We have completed a computer graphic model of human P450c17 based on the x-ray structure of the bacterial P450BM-P. We will now construct a model of P450c21 using this same approach. We have docked steroid substrates into the P450c17 model to confirm that the model predicts the known activities of the enzyme and explains the loss of activity by mutations that occur in patients. We will perform a similar analysis of the P450c21 structure once completed. These models will be tested by site-directed mutagenesis and we will refine the models with these results. Finally, we will identify segments of the two models that appear to confer catalytic specificity, and we will generate chimeric proteins in an attempt to confer the activities of one enzyme upon the other.

细胞色素P450 c17催化17-羟基化和 人肾上腺和肾上腺中C21类固醇的氧化裂解 生殖腺 而肾上腺17-羟化酶的活性仍然相当 出生后恒定，肾上腺裂解酶活性，通过血清反映 硫酸脱氢表雄酮，在8岁左右肾上腺初显时升高 然后在50岁之后逐渐下降。 确定 P450 c17的三维结构将大大提高我们的 理解这两种截然不同的活动是如何 单个蛋白质可以独立调节。 P450 C21是一个相关的 催化21-羟化酶反应的类固醇生成酶。 P450 c17和P450 c21具有高度的序列相似性和相同的基因 结构，并且两者都利用相同的底物（双烯醇酮， 孕酮和它们的17-羟基衍生物）。 的微妙 它们的底物选择性和催化活性的差异 然而，特异性导致不同类固醇的产生， 具有截然不同的生物活性的激素。 我们认为 两种酶的结构-功能比较将产生重要的 深入了解类固醇生成酶的作用和方法， 选择性抑制。 我们已经完成了一个计算机图形 基于细菌的X射线结构的人P450 c17模型 P450 BM-P。我们现在将使用相同的P450 BM-P构建P450 c21的模型。 approach. 我们将类固醇底物对接到P450 c17模型中， 确认该模型预测了酶的已知活性， 解释了患者体内发生的突变导致的活性丧失。 我们 我将对P450 c21结构进行一次类似的分析 完成 这些模型将通过定点突变进行测试 我们将用这些结果来完善模型。 最后我们将 确定两个模型中似乎具有催化作用的部分 特异性，我们将产生嵌合蛋白，试图 将一种酶的活性赋予另一种酶。