PECASE: Mechanistic Studies on Cyclopropane Fatty Acid Synthase

PECASE：环丙烷脂肪酸合成酶的机理研究

• 批准号: 0133826
• 负责人: Squire Booker
• 金额: $ 52.47万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0133826&HistoricalAwards=false
• 关键词: PECASE; Mechanistic; Studies; Cyclopropane; Fatty

Proposal Title: PECASE: Mechanistic Studies on Cyclopropane Fatty Acid SynthaseInstitution: Pennsylvania State Univ University ParkS-adenosyl-L-methionine (AdoMet) is one of the most versatile cellular metabolites used in enzymatic catalysis. Until relatively recently, it has been appreciated primarily as a cellular methylating agent, since it is the primary source of methyl groups for a broad spectrum of biological compounds, including DNA, RNA, proteins, lipids, carbohydrates, and a diverse array of small molecules. AdoMet is also involved in a variety of other interesting transformations. In one class of enzymes, it functions in concert with iron-sulfur clusters to generate enzyme-bound radicals that are intermediates in certain enzymatic reactions. In the project described herein, it functions as a donor of a methylene group rather than a methyl group, in a fascinating reaction catalyzed by the enzyme cyclopropane fatty acid synthase from Escherichia coli. The second substrate is an isolated and unactivated cis olefin present in the unsaturated fatty acid acyl chains of phospholipids. In contrast to methyl transfer, there is very little precedent in the biochemical literature for methylene transfer from AdoMet. All polar mechanisms for the reaction would be expected to involve intermediates that are very high in energy. In addition, since most cellular phospholipids are constituents of phospholipid bilayers, wherein their fatty acid chains are sequestered from the aqueous milieu, it is unclear how this enzyme catalyzes a reaction between two substrates of opposing solubilities. The goal of this project is to address these intriguing questions using a variety of kinetic, mechanistic, and physical techniques, which if successful, will contribute significantly to the general understanding of enzyme reaction mechanisms.This project was originally funded as a CAREER award, and was converted to a Presidential Early Career Award for Engineers and Scientists (PECASE) award in May 2004.

提案标题：PECASE：环丙烷脂肪酸合成酶的机理研究机构：宾夕法尼亚州立大学公园S-腺苷-L-甲硫氨酸（AdoMet）是酶催化中使用最通用的细胞代谢物之一。直到最近，它主要被认为是一种细胞甲基化剂，因为它是多种生物化合物（包括 DNA、RNA、蛋白质、脂质、碳水化合物和各种小分子）甲基的主要来源。 AdoMet 还参与了各种其他有趣的转变。在一类酶中，它与铁硫簇协同作用，产生酶结合自由基，这些自由基是某些酶反应的中间体。在本文描述的项目中，在大肠杆菌环丙烷脂肪酸合酶催化的令人着迷的反应中，它充当亚甲基而不是甲基的供体。第二种底物是存在于磷脂不饱和脂肪酸酰基链中的分离且未活化的顺式烯烃。与甲基转移相反，生化文献中很少有 AdoMet 进行亚甲基转移的先例。预计该反应的所有极性机制都将涉及能量非常高的中间体。此外，由于大多数细胞磷脂是磷脂双层的组成部分，其中它们的脂肪酸链与水环境隔离，因此尚不清楚这种酶如何催化两种溶解度相反的底物之间的反应。该项目的目标是利用各种动力学、机械和物理技术来解决这些有趣的问题，如果成功，将大大有助于对酶反应机制的一般理解。该项目最初是作为职业奖资助的，并于 2004 年 5 月转变为工程师和科学家总统早期职业奖 (PECASE) 奖。