Molybdenum cofactors, enzymes and pathways

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The trace element molybdenum is essential for nearly all organisms and forms the catalytic centre of a large variety of enzymes such as nitrogenase, nitrate reductases, sulphite oxidase and xanthine oxidoreductases. Nature has developed two scaffolds holding molybdenum in place, the iron–molybdenum cofactor and pterin-based molybdenum cofactors. Despite the different structures and functions of molybdenum-dependent enzymes, there are important similarities, which we highlight here. The biosynthetic pathways leading to both types of cofactor have common mechanistic aspects relating to scaffold formation, metal activation and cofactor insertion into apoenzymes, and have served as an evolutionary 'toolbox' to mediate additional cellular functions in eukaryotic metabolism.

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Figure 1: Molybdenum-containing cofactors.
Figure 2: Three-dimensional structures of representative members of molybdenum-containing enzymes.
Figure 3: Biosynthesis of FeMo-co.
Figure 4: Proposed mechanisms for molybdate activation in FeMo-co and Moco biosynthesis.
Figure 5: Biosynthesis of the pyranopterin-based molybdenum cofactors.
Figure 6: Domain structure and function of Moco sulphurase Aba3 from Arabidopsis thaliana.
Figure 7: Human Moco deficiency.


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Support from the Deutsche Forschungsgemeinschaft (G.S., R.R.M.), the Bundeministerium für Bildung und Forschung (G.S.), the Fonds der Chemischen Industrie (G.S.), the European Union (R.R.M.) and the US National Institutes of Health (grant GM-67626; M.W.R.) is gratefully acknowledged, as is the contribution of all co-workers, especially graduate students and post-docs, during the past ten years.

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Schwarz, G., Mendel, R. & Ribbe, M. Molybdenum cofactors, enzymes and pathways. Nature 460, 839–847 (2009) doi:10.1038/nature08302

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