Work in this laboratory has led to the structural characterization of a new pterin cofactor, molybdopterin, which is essential for the function of molybdoenzymes in man and lower organisms. The long-range goal of this project is to fully delineate the molecular biochemistry of the molybdenum cofactor, the complex of Mo and molybdopterin, in relation to human health and development. The importance of this goal is evident from the severe neurological and developmental lesions seen in patients with a genetic deficiency of the cofactor. An important issue to be addressed is whether molybdopterin, the organic component of the Mo cofactor, is totally synthesized de novo or is built up from a dietarily derived pterin precursor. A series of studies using isotopic precursors are proposed to investigate this question. The outcome of these studies could have a bearing on the nutritional requirements of the general human population. The recent discovery of a cell-permeable molybdopterin precursor has made it possible to initiate studies on the possible correction of molybdopterin deficiency in affected individuals and the possibility of increasing tissue levels of molybdopterin in normal individuals. These possibilities will be investigated using cells in culture and experimental animals. Since molybdopterin is a functional prosthetic group of sulfite oxidase, the outcome of these studies could provide mechanisms for increasing resistance to SO2 and sulfites, especially in a large number of asthmatics who display sensitivity to these agents.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Metallobiochemistry Study Section (BMT)
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Duke University
Schools of Medicine
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Leimk├╝hler, Silke; Wuebbens, Margot M; Rajagopalan, K V (2011) The History of the Discovery of the Molybdenum Cofactor and Novel Aspects of its Biosynthesis in Bacteria. Coord Chem Rev 255:1129-1144
Astashkin, Andrei V; Johnson-Winters, Kayunta; Klein, Eric L et al. (2008) Structural studies of the molybdenum center of the pathogenic R160Q mutant of human sulfite oxidase by pulsed EPR spectroscopy and 17O and 33S labeling. J Am Chem Soc 130:8471-80
Doonan, Christian J; Wilson, Heather L; Rajagopalan, K V et al. (2007) Modified active site coordination in a clinical mutant of sulfite oxidase. J Am Chem Soc 129:9421-8
Joshi, M S; Rajagopalan, K V (1994) Specific incorporation of molybdopterin in xanthine dehydrogenase of Pseudomonas aeruginosa. Arch Biochem Biophys 308:331-4
Garrett, R M; Rajagopalan, K V (1994) Molecular cloning of rat liver sulfite oxidase. Expression of a eukaryotic Mo-pterin-containing enzyme in Escherichia coli. J Biol Chem 269:272-6
Pitterle, D M; Johnson, J L; Rajagopalan, K V (1993) In vitro synthesis of molybdopterin from precursor Z using purified converting factor. Role of protein-bound sulfur in formation of the dithiolene. J Biol Chem 268:13506-9
Pitterle, D M; Rajagopalan, K V (1993) The biosynthesis of molybdopterin in Escherichia coli. Purification and characterization of the converting factor. J Biol Chem 268:13499-505
Wuebbens, M M; Rajagopalan, K V (1993) Structural characterization of a molybdopterin precursor. J Biol Chem 268:13493-8
Johnson, J L; Rajagopalan, K V; Lanman, J T et al. (1991) Prenatal diagnosis of molybdenum cofactor deficiency by assay of sulphite oxidase activity in chorionic villus samples. J Inherit Metab Dis 14:932-7
Johnson, J L; Indermaur, L W; Rajagopalan, K V (1991) Molybdenum cofactor biosynthesis in Escherichia coli. Requirement of the chlB gene product for the formation of molybdopterin guanine dinucleotide. J Biol Chem 266:12140-5