MECHANISMS THAT REGULATE ENZYMES THAT METABOLIZE CIS UNSATURATED FATTY ACIDS

调节顺式不饱和脂肪酸代谢酶的机制

• 批准号: 6106722
• 负责人: Thomas Eling
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6106722
• 关键词: animal genetic material tag; enzyme activity; enzyme mechanism; fatty acid metabolism; gene expression; human genetic material tag; human tissue; laboratory rat; ligands; lipopolysaccharides; messenger RNA; nitric oxide; oxygenases; peroxidases; phorbols; prostaglandins; tissue /cell culture; unsaturated fatty acids

Summary of Work: The goal is to develop an understanding of the biochemical mechanisms responsible for the metabolism of arachidonic acid and linoleic acid by these enzymes. Nitric oxide (NO) is reported to enhance prostaglandin formation by enhancement of PGHS activity. We found that NO is a substrate for the peroxidase of PGHS-1 and -2, but it does not enhance the cyclooxygenase activity in vitro. In macrophages, NO does not stimulate the expression of PGHS or alter LPS dependent PGHS-2 expression. Furthermore, NO did not enhance prostaglandin formation in intact cells. We propose htat peroxynitrite, a reaction product of NO and superoxide oxide is responsible. Other studies with PGHS-1 indicate that a tyrosyl radical is formed which could be the reactive intermediate that initiates arachidonic acid oxygenation. Recently, we have shown that NO reacts with the tyrosyl radical converting the radical to a new radical characterized by ESR analysis as an iminoxyl radical. The iminoxyl radical decays to nitrotyrosine resulting in the nitration of the tyrosine moiety on PHS. In addition, its formation of nitrotyrosine is often used as an indicator of oxidative stress. We have identified the specific tyrosine moiety in PHS nitrated by the reaction of NO with tyrosyl radical as Tyrosine-385. This indicates that tyrosine-385 is oxidized to tyrosyl radical during catalysis and suggests this residue is a likely active site or is the site of enzyme inactivation. Understanding the biochemical mechanisms which regulate the activities and expression of these enzymes will provide new insights into potentially controlling or preventing these disease conditions.

工作总结：目标是发展一个