Project Details
Projekt
Charakterisierung eines neu entdeckten mitochondrialen molybdäncofaktorabhängigen Enzymsystems
Subject Area
Pharmacy
Term
from 2009 to 2012
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 111328339
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.
DFG Programme
Research Grants
