Radical enzymes for the biosynthesis of tetrapyrroles

用于四吡咯生物合成的自由基酶

• 批准号: 5406149
• 负责人: Professor Dr. Dieter Jahn
• 金额: --
• 依托单位: Institut für Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2005-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5406149?language=en
• 关键词: Radical; enzymes; biosynthesis; tetrapyrroles

During the biosynthesis of tetrapyrroles like hemes and chlorophylls coproporpyhrinogen III is decarboxylated by two structurally not related enzymes. The oxygen-sensitive coproporpyhrinogen III oxidase HemN uses a [4Fe-4S]-cluster and S-adenosyl-L-methionine to form a substrate radical required for catalysis. The oxygen-dependent HemF uses histidine-coordinated manganese for the same activity. For HemN the natural electron donor(s) and acceptor(s) will be identifed. The redox behavior of the Fe-S-cluster and the location(s) of the substrate radical will be determined spectroscopically. The nature of enzymatic S-adenosyl-L-methionine binding and utilization will be clarified. For HemF missing manganese ligands will be identified. Changes in oxidation state and metal coordination during the reaction of manganese with oxygen and substrate will be analyzed. Potential enzyme and substrate radicals involved in catalysis will be demonstrated. Substituents of the tetrapyrrolic substrate important for the recognition by both enzymes will be evaluated using synthetic analogs. Finally, to understand structure-function relationships the atomic structure of both enzymes must be elucidated using anaerobic crystallisation with substrate analogs and X-ray analysis.

在四吡咯如血红素和叶绿素的生物合成过程中，粪卟啉原III被两种结构上不相关的酶脱羧。氧敏感性粪尿蛋白原III氧化酶HemN使用[4Fe-4S]-簇和S-腺苷-L-甲硫氨酸形成催化所需的底物自由基。氧依赖性HemF使用组氨酸配位的锰进行相同的活性。对于HemN，将鉴定天然电子供体和受体。Fe-S-簇的氧化还原行为和底物自由基的位置将通过光谱确定。酶促S-腺苷-L-甲硫氨酸结合和利用的性质将得到澄清。对于HemF，将鉴定缺失的锰配体。将分析锰与氧和基体反应过程中氧化态和金属配位的变化。潜在的酶和底物自由基参与催化将被证明。将使用合成类似物评估对两种酶的识别重要的四吡咯底物的取代基。最后，为了理解结构-功能关系，必须使用底物类似物的厌氧结晶和X射线分析来阐明这两种酶的原子结构。