Mechanism of ATP Synthase (F F ): Analysis at the level of amino acid residues of subunits.

大肠杆菌的三磷酸腺苷合成酶与线粒体中的三磷酸腺苷合成酶的结构和功能基本相同。该酶的催化部分由5个亚基组成，具有ATPase活性。-lt；F_o&gt；部分有三个亚基，a、b和c，并起到质子通道的作用。这8个亚基由UNC操纵子编码，DNA序列由本课题组确定。我们分离了150多个UNC操纵子的突变体，并建立了快速检测其改变氨基酸残基的方法。在本研究项目中，我们在氨基酸残基水平上对该酶的作用机理和组装进行了研究。(1)利用抑制剂和突变体分析了该酶的催化协同性。我们的结果表明，该酶的单位和多位酶的两种作用机制可以明显分离。突变研究表明Arg-246或其邻近区域对催化协同作用是重要的。(2)广泛分析了装配突变(In；lt；β&gt；和&lt；Gamma&gt；亚基)，并提出了一种新的酶模型。(3)对&lt；F_o&gt；亚基的突变进行了广泛的分析。提出了残基参与质子接力系统。

The ATP synthase of Escherichia coli has essentially the same structure and functions as those found in mitochondria. The catalytic portion of the enzyme, <F_1> , consists of 5 subunits <alpha> , <beta> , <gamma> , <delta> and <epsilon> , and has ATPase activity. The <F_o> portion has three subunits, a, b and c, and functions as a proton channel. The eight subunits are encoded by the unc operon which DNA sequence was determined by our group. We isolated more than 150 mutants of unc operon and established rapid method to determine their altered amino acid residues. In this research project we studied mechanism and assembly of the enzyme at the level of amino acid residues.(1) We have analyzed catalytic cooperativity of the enzyme using inhibitors and mutants. Our results showed that the two mechanisms uni- and multi- site catalyses of the enzyme can be clearly separated. Mutation studies indicated that Arg-246 or the region in its vicinity is important for the catalytic cooperativity.(2) Assembly mutations (in <beta> and <gamma> subunits) were analyzed extensively, and a new model for the enzyme was proposed.(3) Extensive analysis of mutations in <F_o> subunits was carried out. Residues participating proton relay system were proposed.