Winterschlafende Bären, Antibiotika und die Evolution des Ribosoms (Nobel-Aufsatz)

Functional Assemblies Emerging in Complex Mixtures of Peptides and Nucleic Acid-Peptide Chimeras

Striking synergy between nucleic acids and proteins is exhibited in living cells. Whether such mutual activity can be performed using simple supramolecular nucleic acid-peptide (NA-pep) architectures remains a mystery. To shed light on this question, we studied the emergence of a primitive synergy in assemblies of short DNA-peptide chimeras. Specifically, we characterized multiple structures forming along gradual mixing trajectory, in which a peptide solution was seeded with increasing amounts of NA-pep chimeras. We report on the systematic change from β-sheet-peptide-based fibrillar architectures into the spherical structures formed by the conjugates. Remarkably, we find that through forming onion-like structures, the conjugates exhibit increased DNA hybridization stability and bind small molecules more efficiently than the peptides or DNA alone. A brief discussion highlights the implications of our findings for the production of new materials and for research on the origin of life.

Molecular Switching in Confined Spaces: Effects of Encapsulating the DHA/VHF Photo-Switch in Cucurbiturils

Confinement of reactive chemical species uniquely affects chemical reactivity by restricting the physical space available and by restricting access to interactions with the solvent. In Nature, for example, confined protein binding pockets govern processes following photoisomerization reactions and the isomerizations themselves. Here we describe the first example of a dihydroazulene/vinylheptafulvene (DHA/VHF) photo-switch functioning in water, and we show how its switching behavior is strongly influenced by supramolecular interactions with a series of cucurbit[n]uril (CB) host molecules. In CB7 inclusion complexes, the kinetics of the thermal VHF-to-DHA back-reaction is accelerated, while in CB8 inclusion complexes, the kinetics is slowed down as compared to the free photo-switch. The effect of the CB encapsulation of the photo-switch can be effectively canceled by introducing a guest that binds the CB more strongly. According to DFT calculations, a stabilization of the reactive s-cis VHF conformer relative to the s-trans VHF appears to be a contributing factor responsible for the accelerated back-reaction when encapsulated in CB7.

Mechanically Interlocked Molecules (MIMs)-Molecular Shuttles, Switches, and Machines (Nobel Lecture)

Chemistry welcomes a new bond: The mechanical bond has endowed molecules with component parts whose movements can be controlled and monitored. In his Nobel Lecture, J. F. Stoddart describes how being able to template the formation of mechanically interlocked molecules has led to the design and synthesis of shuttles, switches, and machines at the nanoscale.

Wholly Synthetic Molecular Machines

The past quarter of a century has witnessed an increasing engagement on the part of physicists and chemists in the design and synthesis of molecular machines de novo. This minireview traces the development of artificial molecular machines from their prototypes in the form of shuttles and switches to their emergence as motors and pumps where supplies of energy in the form of chemical fuel, electrochemical potential and light activation become a minimum requirement for them to function away from equilibrium. The challenge facing this rapidly growing community of scientists and engineers today is one of putting wholly synthetic molecules to work, both individually and as collections. Here, we highlight some of the recent conceptual and practical advances relating to the operation of wholly synthetic rotary and linear motors.

Generation of RNA molecules by a base-catalysed click-like reaction

The problem of the abiotic origin of RNA from prebiotically plausible compounds remains unsolved. As a potential partial solution, we report the spontaneous polymerization of 3',5'-cyclic GMP in water, in formamide, in dimethylformamide, and (in water) in the presence of a Brønsted base such as 1,8-diazabicycloundec-7-ene. The reaction is untemplated, does not require enzymatic activities, is thermodynamically favoured and selectively yields 3',5'-bonded ribopolymers containing as many as 25 nucleotides. We propose a reaction pathway on the basis of 1) the measured stacking of the 3',5'-cyclic monomers, 2) the activation by Brønsted bases, 3) the determination (by MALDI-TOF mass spectrometry, by (31)P NMR, and by specific ribonucleases) of the molecular species produced. The reaction pathway has several of the attributes of a click-like reaction.