English Abstract, FWF Project 19764 Glyceryl-Ether Monooxygenase,
Ernst R. Werner , Divison of Biological Chemistry, Biocenter, Medical University of Innsbruck
Glyceryl-ether monooxgenase is an enzyme activity found throughout the body of mammals, with highest activities in the liver. It cleaves glyceryl-ether lipids to glycerol and the respective aldehyde by a monooxygenase type reaction with the aid of tetrahydrobiopterin, which is essential for the reaction. Etherlipids are known to be membrane constituents, but also can serve as signal mediators. Tetrahydrobiopterin is a low molecular weight cofactor of aromatic amino acid hydroxylases and nitric oxide synthases. Tetrahydrobiopterin shows structural similarity to the vitamins folic acid and riboflavin, but is biosynthesized in mammals from guanosine 5' triphosphate.
Although glyceryl-ether monooxygenase activity has been repeatedly detected by several independent research groups, no sequence has been associated with this enzyme activity so far, and hence no sequence and no position of the gene in the human nor in another mammalian genome has been assigned. In addition, the physiological role of the glyceryl-ether monooxygenase has not been studied yet.
The aim of the present project is to assign a sequence in the almost complete mammalian genomes to this enzyme, and to use this information to study the biochemistry, physiological role and potential association to diseases with unknown genetic background. For this purpose we plan to purify the glyceryl-ether monooxygenase protein in its active form, and to determine its sequence. To enable a successful purification of the enzyme, we have developed a novel, rapid and sensitive enzyme assay on the basis of a fluorescent substrate kindly designed and provided by Albin Hermetter, University of Technology, Graz, Austria. In order to unravel the physiological significance of glyceryl-ether monooxygenase, we plan to study mice with a mutation in the gene encoding this enzyme, and to study the effects of downregulation and overexpression of the respective gene in cultivated mammalian cells. We also plan to generate high amounts of pure protein by recombinant expression techniques to study its structure-function relationships, with special emphasis on the role of the tetrahydrobiopterin cofactor in the reaction.
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