由酶催化的 [4+2] 循环添加是氨酸A生物合成的关键步骤
Hak Joong Kim1, Mark W Ruszczycky, Sei-hyun Choi
1Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Nature
|May 6, 2011
概括
研究人员确定了SpnF,这是第一个专门的酶,在spinosyn A生物合成中催化了Diels-Alder反应. 这种酶特别加速了环烯环的形成,澄清了天然产品合成的关键步骤.
科学领域:
- 生物化学 生物化学
- 有机化学 有机化学
- 酶学 是一种酶学.
背景情况:
- 迪尔斯-阿尔德反应对于合成含有环素的天然产品至关重要.
- 迪尔斯-阿尔德反应的酶催化是罕见的,以前只涉及四种酶.
- 现有的酶往往具有多种活动,掩盖了它们在循环添加中的特定作用.
研究的目的:
- 为了研究复杂的自然产物spinosyn A的生物合成.
- 为了识别和描述参与形成spinosyn A核心结构的酶.
- 为了确定特定的酶是否在这个途径中催化了Diels-Alder循环添加反应.
主要方法:
- 研究了Saccharopolyspora spinosa中的spinosyn A的生物合成.
- 识别并净化了循环酶 SpnF.
- 进行了动力学分析,以确定SPNF的催化活性和速率增强.
- 识别了spnL酶用于随后的交叉桥接步骤.
主要成果:
- 确定了SpnF作为一种催化一个跨环 [4+2] 循环添加的循环酶,用于spinosyn A的循环烯环.
- 在这种特定反应中,SpnF显著提高了500倍的速率.
- 确定SPNL负责最后的交叉桥梁步骤,完成四环核.
- 该酶是第一个专门用于迪尔斯-阿尔德催化作用的独立酶.
结论:
- SpnF是第一个特征化的酶,在体外专门催化迪尔斯-阿尔德 [4+2] 循环添加.
- 这项研究充分阐明了Spinosyn A.中的perhydro-as-indacene部分的形成.
- 这项工作提供了天然产品生物合成中酶介导的迪尔斯-阿尔德反应的关键例子.
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