ChemSystemsChem最新文献

Peptides have essential structural and catalytic functions in living organisms. The formation of peptides requires the overcoming of thermodynamic and kinetic barriers. In recent years, various formation scenarios that may have occurred during the origin of life have been investigated, including iron(III)-catalyzed condensations. However, iron(III)-catalysts require elevated temperatures and the catalytic activity in peptide bond forming reactions is often low. It is likely that in an anoxic environment such as that of the early Earth, reduced iron compounds were abundant, both on the Earth's surface itself and as a major component of iron meteorites. In this work, we show that reduced iron activated by acetic acid mediates efficiently peptide formation. We recently demonstrated that, compared to water, liquid sulfur dioxide (SO₂) is a superior reaction medium for peptide formations. We thus investigated both and observed up to four amino acid/peptide coupling steps in each solvent. Reaction with diglycine (G₂) formed 2.0 % triglycine (G₃) and 7.6 % tetraglycine (G₄) in 21 d. Addition of G₃ and dialanine (A₂) yielded 8.7 % G₄. Therefore, this is an efficient and plausible route for the formation of the first peptides as simple catalysts for further transformations in such environments.

Nature uses dynamic, molecular self-assembly to create cellular architectures that adapt to their environment. For example, a guanosine triphosphate (GTP)-driven reaction cycle activates and deactivates tubulin for dynamic assembly into microtubules. Inspired by dynamic self-assembly in biology, recent studies have developed synthetic analogs of assemblies regulated by chemically fueled reaction cycles. A challenge in these studies is to control the interplay between rapid disassembly and kinetic trapping of building blocks known as dynamic instabilities. In this work, we show how molecular design can tune the tendency of molecules to remain trapped in their assembly. We show how that design can alter the dynamic of emerging assemblies. Our work should give design rules for approaching dynamic instabilities in chemically fueled assemblies to create new adaptive nanotechnologies.

Absorption of ultraviolet (UV) radiation can trigger a variety of photophysical and photochemical reactions in nucleic acids. In the prebiotic era, on the surface of the early Earth, UV light could have played a major role in the selection of the building blocks of life via a balance between synthetic and destructive pathways. As nucleic acid monomers assembled into polymers, their survival and facility for non-enzymatic replication hinged on their photostability and the ability for self-repair of lesions, e. g., by UV-induced charge transfer. Such photoprocesses are known to be sequence-dependent and could have led to an additional prebiotic selection of the genetic sequence pools available to the earliest life forms. This review summarizes the photophysical processes in nucleic acids upon the absorption of a UV photon and their implications for chemical and genetic selection at the emergence of life and the origin of translation.

For the emergence of life, the abiotic synthesis of RNA from its monomers is a central step. We found that in alkaline, drying conditions in bulk and at heated air-water interfaces, 2′,3′-cyclic nucleotides oligomerised without additional catalyst, forming up to 10-mers within a day. The oligomerisation proceeded at a pH range of 7–12, at temperatures between 40–80 °C and was marginally enhanced by K⁺ ions. Among the canonical ribonucleotides, cGMP oligomerised most efficiently. Quantification was performed using HPLC coupled to ESI-TOF by fitting the isotope distribution to the mass spectra. Our study suggests a oligomerisation mechanism where cGMP aids the incorporation of the relatively unreactive nucleotides C, A and U. The 2′,3′-cyclic ribonucleotides are byproducts of prebiotic phosphorylation, nucleotide syntheses and RNA hydrolysis, indicating direct recycling pathways. The simple reaction condition offers a plausible entry point for RNA to the evolution of life on early Earth.

This Concept is focused on the key features of dissipative dynamic combinatorial chemistry (DDCC). DDCC deals with transient libraries of compounds, maintained out-of-equilibrium by the consumption of a fuel, whose composition changes upon the selection pressure of kinetic and/or thermodynamic processes. Concepts and definitions of kinetic and thermodynamic dissipative dynamic libraries (“KDDL” and “TDDL”), are introduced and illustrated by a number of actual cases, thus showing the consistency of the present approach. Such concepts and definitions can help establish a common language for this emerging field, which, in our view, has the potential to become highly relevant to supramolecular chemistry.

Metabolites are the set of substances produced or utilized in the biochemical process of metabolism known to perform diverse physiological functions in every living organism. As very simple molecules, metabolites can self-assemble into functional materials for biomedical and nanotechnology applications. Simple amino acid-based crystals exhibit interesting physicochemical properties of piezoelectricity, fluorescence and optical waveguiding. Combinations of metal-coordinated metabolites display catalytic properties mimicking natural enzymes for chemical reactions and environmental remediation. Furthermore, excessive accumulation of metabolites spontaneously forms toxic assemblies implicated in the pathogenesis of metabolic and neurodegenerative diseases. Herein, we mainly review the progress of recent three years on the assembly of minimalistic metabolite-based building blocks into bionanomaterials and their potential applications in energy harvesting, optical waveguiding, enzymatic catalysis, and biomedicine. We hope this review can promote the understanding and development of metabolite materials to meet functional requirements.

The front cover artwork is provided by Wolfgang Weigand's group at Friedrich Schiller University Jena and was designed by Mario Grosch. The image shows a hypothetical version of the Earth's early surface, where mackinawite produced from the reaction between iron and sulfur in water can react with C₁ substrates like HCN to form CH₄, NH₃, CH₃SH and CH₃CHO. Read the full text of the Research Article at 10.1002/syst.202200010.

The Front Cover shows a possible version of Earth's early surface, where mackinawite formed by the reaction between iron and sulfur can subsequently reduce HCN into organic compounds like CH₄, NH₃, CH₃SH and CH₃CHO and thereby provide important precursors for the origin of life. Design by Mario Grosch. More information can be found in the Research Article by Markus Ribbe, Yilin Hu, Oliver Trapp, Christian Robl, Wolfgang Weigand and co-workers.

The use of “fuel” compounds to drive chemical systems out of equilibrium is currently of interest because of the potential for temporally controlled, responsive behavior. We have recently shown that transiently formed crown ethers exhibit counterintuitive templation effects when generated in the presence of alkali metal cations: “matched” cations, such as K⁺ with an 18-crown-6 analogue, suppress the formation of the macrocycles (negative templation). In this work, we describe two macrocyclic diacids that, on treatment with carbodiimides, give transient macrobicyclic cages analogous to polyether cages. Negative templation effects are observed for the smaller cage when generated in the presence of K⁺ and Na⁺, but there is a weak, but reproducible, positive templation effect in the presence of Li⁺. The larger cage behaves similarly in the presence of Li⁺, K⁺, Rb⁺, and Cs⁺, but differently with Na⁺, which appears to bind to both the cage and the initial macrocycle.

Nucleotides play a fundamental role in organisms, from adenosine triphosphate (ATP), the body‘s main source of energy, to cofactors of enzymatic reactions (e. g. coenzyme A), to nucleoside monophosphates as essential building blocks of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Although nucleotides play such an elemental role, there is no pathway to date for the selective formation of nucleoside 5′-monophosphates. Here, we demonstrate a selective reaction pathway for 5’ mono-phosphorylation for all canonical purine and pyrimidine bases under exceptionally mild prebiotic relevant conditions in water and without using a condensing agent. The pivotal reaction step involves activated imidazolidine-4-thione phosphates. The selective formation of non-cyclic mono-phosphorylated nucleosides represents a novel and unique route to nucleotides and opens exciting perspectives in the study of the origins of life.