Pterin-Containing Tungsten Enzymes

Pterin, see also Tungsten, enzymes, pterin-containing... 

Bioinorganic Chemistry of Pterin-Containing Molybdenum and Tungsten Enzymes John H. Enemark and Charles G. Young... 

Another factor that characterizes molybdenum and tungsten enzymes is that instead of using the metal itself, directly coordinated to amino acid side-chains of the protein, an unusual pterin cofactor, Moco, is involved in both molybdenum- and tungsten-containing enzymes. The cofactor (pyranopterin-dithiolate) coordinates the metal ion via a dithiolate side-chain (Figure 17.2). In eukaryotes, the pterin side-chain has a terminal phosphate group, whereas in prokaryotes, the cofactor (R in Figure 17.2) is often a dinucleotide. 

Bioinorganic Chemistry of Pterin-Containing Molybdenum and Tungsten Enzymes... 

BIOINORGANIC CHEMISTRY OF PTERIN-CONTAINING MOLYBDENUM AND TUNGSTEN ENZYMES ... 

This chapter is restricted to the bioinorganic chemistry of pterin-containing molybdenum and tungsten enzymes. Primary emphasis is given to recent results and to the interplay of model and enzyme chemis-... 

The chapter consists of nine sections. Sections II through VII deal with the pterin-containing molybdenum enzymes. Biochemical and model studies of molybdopterin, Mo-co, and related species are described in Section II. In Section III, we briefly survey physical and spectroscopic techniques employed in the study of the enzymes, and consider their impact upon the current understanding of the coordination about the molybdenum atom in sulfite oxidase and xanthine oxidase. Model studies are described in Sections IV and V. Section IV concentrates on structural and spectroscopic models, whereas Section V considers aspects of the reactivity of model and enzyme systems. The xanthine oxidase cycle (Section VI) and facets of intramolecular electron transfer in molybdenum enzymes (Section VII) are then treated. Section VIII describes the pterin-containing tungsten enzymes and the evolving model chemistry thereof Future directions are addressed in Section IX. 

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