Coenzymes and Their Role in the Evolution of Life

The evolution of coenzymes, or their impact on the origin of life, is fundamental for understanding our own existence. Having established reasonable hypotheses about the emergence of prebiotic chemical building blocks, which were probably created under palaeogeochemical conditions, and surmising that these smaller compounds must have become integrated to afford complex macromolecules such as RNA, the question of coenzyme origin and its relation to the evolution of functional biochemistry should gain new impetus. Many coenzymes have a simple chemical structure and are often nucleotide-derived, which suggests that they may have coexisted with the emergence of RNA and may have played a pivotal role in early metabolism. Based on current theories of prebiotic evolution, which attempt to explain the emergence of privileged organic building blocks, this Review discusses plausible hypotheses on the prebiotic formation of key elements within selected extant coenzymes. In combination with prebiotic RNA, coenzymes may have dramatically broadened early protometabolic networks and the catalytic scope of RNA during the evolution of life

On the Evolutionary History of the Twenty Encoded Amino Acids

α-Amino acids are essential molecular constituents of life, twenty of which are privileged because they are encoded by the ribosomal machinery. The question remains open as to why this number and why this 20 in particular, an almost philosophical question that cannot be conclusively resolved. They are closely related to the evolution of the genetic code and whether nucleic acids, amino acids, and peptides appeared simultaneously and were available under prebiotic conditions when the first self-sufficient complex molecular system emerged on Earth. This report focuses on prebiotic and metabolic aspects of amino acids and proteins starting with meteorites, followed by their formation, including peptides, under plausible prebiotic conditions, and the major biosynthetic pathways in the various kingdoms of life. Coenzymes play a key role in the present analysis in that amino acid metabolism is linked to glycolysis and different variants of the tricarboxylic acid cycle (TCA, rTCA, and the incomplete horseshoe version) as well as the biosynthesis of the most important coenzymes. Thus, the report opens additional perspectives and facets on the molecular evolution of primary metabolism

Bioorthogonal metal-free click-ligation of cRGD-pentapeptide to alginate

Click reactions have become very common and powerful ligation techniques, of which 1,3-dipolar cycloadditions have most frequently been employed. Since metal-mediated cycloadditions are incompatible in biomedical applications due to toxicity issues associated with transition metals like copper, metal-free variants provide important alternatives. The metal-free conjugation process is studied in detail with special emphasis put on the reaction progress. This report unfolds the first aqueous metal-free "click" conjugation of a cyclic RGD-pentapeptide with the biomacromolecule alginate, creating a "smart" bioactive polymer with potential applications in biomedicine. © 2012 The Royal Society of Chemistry

Synthetic terpenoids in the world of fragrances: Iso E Super® is the showcase

The history of fragrances is closely associated with the chemistry of terpenes and terpenoids. For thousands of years mankind mainly used plant extracts to collect ingredients for the creation of perfumes. Many of these extracts contain complex mixtures of terpenes, that show distinct olfactoric properties as pure compounds. When organic synthesis appeared on the scene, the portfolio of new scents increased either in order to substitute natural fragrances without change of olfactoric properties or to broaden the scope of scents. This short review describes the story of the most successful synthetic fragrance ever which is called Iso E Super® as it is an ingredient in a large number of perfumes with varying percentages and is the first example being used as a pure fragrance. Structurally, it is related to natural terpenes like many other synthetic fragrances. And indeed, the story began with a classic in the field of fragrances, the natural product ionone

A Stable and Safe Form of Iodine Azide: Polymer-Bound Bisazidoiodate(I)

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Ten key issues in modern flow chemistry

Ten essentials of synthesis in the flow mode, a new enabling technology in organic chemistry, are highlighted as flashlighted providing an insight into current and future issues and developments in this field. © The Royal Society of Chemistry 2011

Lipoxygenase-catalysed co-oxidation for sustained production of oxyfunctionalized terpenoids

Lipoxygenases (LOX) catalyse allylic oxidations and epoxidations of a co-substrate in the presence of an unsaturated fatty acid containing a 1,4-pentadiene moiety. One- and two-step enzyme assays were established to verify the role or involvement of LOX in such co-oxidations. It was shown that LOX is only involved in the formation of reactive hydroperoxides, but not in the oxidation of a co-substrate, assuming a mechanism involving free peroxy radicals for the latter. Ten mono- and sesquiterpenes were used as co-substrates and the resulting products were analysed by mass spectrometry. A semi-preparative approach was developed using (+)-valencene as an example, and the resulting products were isolated by preparative GC and their structures elucidated by NMR spectroscopy

Oxidative azidations of phenols and ketones using iodine azide after release from an ion exchange resin

The oxidative oligoazidation of phenols and ketones using iodine azide (IN3) provided by its release from an ion exchange resin is reported. Preliminary mechanistic studies indicate a previously unknown reactivity of iodine azide toward phenols and ketones. © The Royal Society of Chemistry 2021

Microwave-accelerated Mizoroki-Heck and Sonogashira cross- coupling reactions in water using a heterogeneous palladium(II)-precatalyst

The catalytic activity of a 2-pyridinealdoxime-based Pd(II)-complex covalently anchored via the oxime moiety to a glass/ polymer composite material was evaluated both under thermal as well as microwave (μw) irradiating conditions in water in Mizoroki-Heck as well as Sonogashira C-C cross-coupling reactions. Synthesis of benzo[b]furan derivatives via Sonogashira cross coupling reaction was achieved when ortho-halo-phenols were employed as aryl halides. The stability and reusability of this Pd-precatalyst was part of the present study. ©ARKAT USA, Inc.DFG/Ki 397/6-1Alexander-von-Humboldt Foundatio