Over time, organisms have evolved strategies to cope with the abundance of dioxygen on Earth. Oxygen-utilizing enzymes tightly control the reactions involving O2 mostly by modulating the reactivity of their cofactors. Flavins are extremely versatile cofactors that are capable of undergoing redox reactions by accepting either one electron or two electrons, alternating between the oxidized and the reduced states. The physical and chemical principles of flavin-based chemistry have been investigated widely. In the following pages we summarize the state of the art on a key area of research in flavin enzymology: the molecular basis for the activation of O2 by flavin-dependent oxidases and monooxygenases. In general terms, oxidases use O2 as an electron acceptor to produce H2O2, while monooxygenases activate O2 by forming a flavin intermediate and insert an oxygen atom into the substrate. First, we analyze how O2 reaches the flavin cofactor embedded in the protein matrix through dedicated access pathways. Then w...

Same Substrate, Many Reactions: Oxygen Activation in Flavoenzymes

Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C–H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally,...

/pdf/enzymatic-halogenation-and-dehalogenation-reactions-5a5tbnfi0d.pdf

Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse

Nature has evolved halogenase enzymes to regioselectively halogenate a diverse range of biosynthetic precursors, with the halogens introduced often having a profound effect on the biological activity of the resulting natural products. Synthetic endeavors to create non-natural bioactive small molecules for pharmaceutical and agrochemical applications have also arrived at a similar conclusion: halogens can dramatically improve the properties of organic molecules for selective modulation of biological targets in vivo. Consequently, a high proportion of pharmaceuticals and agrochemicals on the market today possess halogens. Halogenated organic compounds are also common intermediates in synthesis and are particularly valuable in metal-catalyzed cross-coupling reactions. Despite the potential utility of organohalogens, traditional nonenzymatic halogenation chemistry utilizes deleterious reagents and often lacks regiocontrol. Reliable, facile, and cleaner methods for the regioselective halogenation of organic co...

/pdf/development-of-halogenase-enzymes-for-use-in-synthesis-3mzvp82xg4.pdf

Development of Halogenase Enzymes for Use in Synthesis

Mass spectrometry instruments measure the mass to charge ratio of ions, from which we infer the molecular structures. They are key tools for investigating the incredibly diverse chemistry that is associated with biological systems. Typically, when one thinks about the chemistry of biology, one thinks of biochemical pathways, structural lipids or carbohydrates. However, numerous additional chemistries are part of various biological systems. These include molecules that originate from diet, water treatment, personal care, medications, pollutants and environmental exposures including plastics, clothes and furniture. These principles apply not only to people but to all of biology, from the worms at the bottom of the ocean, to the bacteria in our belly buttons and to the birds that fly over Mount Everest. In the past decade, our capacity to inventory the chemistry of biological systems using mass spectrometry at a global level has been revolutionized. In this Review, we discuss the informatics and hardware tools that are available for small-molecule analysis and provide an overview of the tools that could transform how we study the chemistry of biological systems; perhaps in the future this will be as easy as taking a photograph with a smartphone. An untargeted mass spectrometry analysis of a biological sample will detect both biological molecules and compounds that are derived from, for example, diet and the environment. This Review examines the design of such experiments, how to process and interpret the vast amount of data that are produced, and how far we are from being able to use mass spectrometry to inventory the world around us.

Global chemical analysis of biology by mass spectrometry

/pdf/current-applications-of-suzuki-miyaura-coupling-reaction-in-1dka4ljnou.pdf

Current Applications of Suzuki–Miyaura Coupling Reaction in The Total Synthesis of Natural Products: An update

Polybrominated diphenyl ethers (PBDEs) and polybrominated bipyrroles are natural products that bioaccumulate in the marine food chain. PBDEs have attracted widespread attention because of their persistence in the environment and potential toxicity to humans. However, the natural origins of PBDE biosynthesis are not known. Here we report marine bacteria as producers of PBDEs and establish a genetic and molecular foundation for their production that unifies paradigms for the elaboration of bromophenols and bromopyrroles abundant in marine biota. We provide biochemical evidence of marine brominases revealing decarboxylative-halogenation enzymology previously unknown among halogenating enzymes. Biosynthetic motifs discovered in our study were used to mine sequence databases to discover unrealized marine bacterial producers of organobromine compounds.

/pdf/biosynthesis-of-polybrominated-aromatic-organic-compounds-by-2tw74eaqbg.pdf

Dennis Poth

Papers

Biosynthesis of polybrominated aromatic organic compounds by marine bacteria