Charakterisierung eines neu entdeckten mitochondrialen molybdäncofaktorabhängigen Enzymsystems

“线粒体偕胺肟还原组分”（mARC）是一种含钼酶，于2006年在我们的实验室中被发现。除了mARC，人类体内已知的钼酸酶只有三种。该酶能够与细胞色素b5 （cyt b5）和NADH细胞色素b5还原酶（b5 Red）一起还原n -羟基化化合物。几乎所有真核生物基因组都编码两种mARC酶（mARC1和mARC2），它们的氨基酸序列非常相似。此外，这两种mARC酶都能与cyt b5和b5 Red一起还原n -羟基化化合物。根据我们以前的工作和出版物，酶“mARC”已经在科学界成功建立。因此，我们提出的“mARC”命名于2011年10月被HUGO基因命名委员会（HGNC）采纳。钼辅助因子依赖酶系统最初是在研究n -还原性药物代谢过程中发现的。这种参与药物代谢现已得到很好的研究，因此我们的主要目标是探索酶系统的生理功能。我们提出的项目主要基于我们以前使用分离的重组酶或亚细胞细胞器进行的体外研究。为了更好地评估这种酶系统的生理相关性，我们未来的研究应该主要在细胞系统中进行，并使用我们的marc敲除小鼠模型。特别是应考虑以下几个方面：(i)是否有一种或两种mARC酶参与n还原途径？（ii）酶系统是否是一种细胞保护机制，防止诱变碱类似物进入细胞的核酸？（iii）酶系统是否调节l -精氨酸和NO的代谢，从而参与糖尿病/糖尿病肾病？（iv）线粒体和过氧化物酶体的亚细胞定位是否暗示了mARC与活性氧复杂代谢的潜在联系？由于含marc的酶系统在n -羟基化官能团药物的代谢中起着核心作用，我们的额外目标是：(v) n -羟基化苯胺衍生物的还原解毒反应的表征。在这种情况下，应该考虑到n -还原酶系统的遗传多态性。（六）底物化学结构与还原酶活性之间定量构效关系的研究。这一信息以后可用于合理开发所谓的“偕胺肟”前药。我们计划的工作是（vii）在生物化学光谱上对活性中心和功能重要的蛋白质序列基序进行表征，以及（viii）对mARC酶的原子结构的阐明将有助于对这类新型酶的一般理解。

The "mitochondrial amidoxime reducing component" (mARC) is a molybdenum-containing enzyme, that was discovered in our labs in 2006. Besides mARC, only three other molybdoenzymes are known in humans. This enzyme is able to reduce N-hydroxylated compounds together with cytochrome b5 (cyt b5) and NADH cytochrome b5 reductase (b5 Red). Almost all eukaryotic genomes encode for two mARC enzymes (mARC1 and mARC2), which are very similar in respect to their amino acid sequence. In addition, both mARC enzymes are able to reduce N-hydroxylated compounds together with cyt b5 and b5 Red.Based on our previous work and publications the enzyme "mARC" is has been successfully established in the scientific world. Thus, the designation "mARC" proposed by us was adopted by the HUGO Gene Nomenclature Committee (HGNC) in October 2011. The molybdenumcofactor-dependend enzyme system was originally discovered during investigations of N-reductive drug metabolism. This involvement in drug metabolism is now well investigated, our primary objective is therefore the exploration of the physiological function of the enzyme system. Our proposed projects are primarily based on our previous in vitro studies using isolated recombinant enzymes or subcellular organelles. In order to better assess the physiological relevance of this enzyme system our future studies should be carried out mainly with cellular systems and also using our mARC-knockout mouse model. In particular the following aspects should be considered: (i) Are one or both mARC enzymes involved in the N-reductive pathway? (ii) Is the enzyme system a cellular protection mechanism that prevents incorporation of mutagenic base analogues into the nucleic acids of the cell? (iii) Does the enzyme system modulates the metabolism of L-arginine and NO and is therefore involved in diabetes/diabetic nephropathy? (iv) Is the subcellular localization in mitochondria and peroxisomes a hint of a potential connection of mARC with the complex metabolism of reactive oxygen species? As the mARC-containing enzyme system plays a central role in the metabolism of drugs with N-hydroxylated functional groups, our additional aims are: (v) The characterization of the reductive detoxification reactions of N-hydroxylated aniline derivatives. In this context genetic polymorphisms of the N-reductive enzyme system should be taken into account. (vi ) The investigation of quantitative structure-activity relationships between the chemical structure of the substrates and the reductase activity. This information could be later applied to the rational development of so-called "amidoxime" prodrugs. Our planned work to (vii) characterize biochemical-spectroscopically both the active center and functionally important protein sequence motifs, and (viii) the elucidation of the atomic structure of mARC enzymes will contribute to the general understanding of this novel class of enzymes.