Since the discovery of the first examples of 2-oxoglutarate-dependent oxygenase-catalysed reactions in the 1960s, a remarkably broad diversity of alternate reactions and substrates has been revealed, and extensive advances have been achieved in our understanding of the structures and catalytic mechanisms. These enzymes are important agrochemical targets and are being pursued as therapeutic targets for a wide range of diseases including cancer and anemia. This book provides a central source of information that summarizes the key features of the essential group of 2-oxoglutarate-dependent dioxygenases and related enzymes. Given the numerous recent advances and biomedical interest in the field, this book aims to unite the latest research for those already working in the field as well as to provide an introduction for those newly approaching the topic, and for those interested in translating the basic science into medicinal and agricultural benefits. The book begins with four broad chapters that highlight critical aspects, including an overview of possible catalytic reactions, structures and mechanisms. The following seventeen chapters focus on carefully selected topics, each written by leading experts in the area. Readers will find explanations of rapidly evolving research, from the chemistry of isopenicillin N synthase to the oxidation mechanism of 5-methylcytosine in DNA by ten-eleven-translocase oxygenases.

Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenases utilize a non-heme mononuclear Fe(II) cofactor to catalyze oxidative transformations of unreactive aliphatic carbon centers in a wide variety of biological substrates. The 2OG cosubstrate allows the enzyme to access the oxidizing potential of molecular oxygen to generate a highly reactive Fe(IV)-oxo (ferryl) intermediate. This species is able to abstract an H-atom from the substrate and, in the most common outcome hydroxylation the enzyme subsequently couples the resulting OH group to a carbon-centered radical on the substrate. Excitingly, the biosynthetic capacity of this platform has expanded to include desaturation, C-O/C bond formation, halogenation, endoperoxidation, epoxidation, stereo-inversion, and even the formation of ethylene. The Fe/2OG oxygenases are considered ideal candidates for biotechnology applications owing to their catalytic diversity, simple and readily available cofactors/cosubstrates, and ability to activate inert C-H bonds. To capitalize on this promise and successfully harness this enzyme scaffold for biotechnology purposes, it is necessary to obtain detailed mechanistic and structural information, particularly for non-hydroxylation systems. The mechanism of OH installation by the Fe/2OG oxygenases is largely understood. In the non-hydroxylases reactivity likely diverges after the substrate hydrogen-atom transfer (HAT) step, resulting in alternate transformation of the carbon-centered radical. It is likely that tight spatial control of the substrate HAT target and the oxygen-derived ligands via interaction with specific active site residues and other components of the Fe coordination sphere are crucial for controlling reaction outcome. Although many Fe/2OG hydroxylases are well-characterized via x-ray crystallography, comprehensive high-resolution structural data for complete enzyme-substrate reactant complexes is lacking for non-hydroxylation systems. Here, we will explore the structural properties of non-canonical Fe/2OG oxygenases, in particular the features that dictate reactivity. A novel set of halogenase crystal structures revealed important active site features for selective catalysis. These findings subsequently allowed for the first successful demonstration of novel halogenation activity from a hydroxylating scaffold. Furthermore, crystallographic snapshots of a hydroxylating system allowed for the visualization of a previously unobserved intermediate and new structural probe for the elusive ferryl species. This work has enabled development of universal hypotheses for control of reaction outcome in these enzymes.