scholarly journals A metal–peptide capsule by multiple ring threading

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Tomohisa Sawada ◽  
Yuuki Inomata ◽  
Koya Shimokawa ◽  
Makoto Fujita
Keyword(s):  
Molecular Machines ◽  
Crossing Number ◽  
Peptide Folding ◽  
Current Interest ◽  
Biological Functions ◽  
Interlocked Molecules ◽  
Chemical Structures ◽  
Virus Capsids ◽  
Molecular Capsule ◽  
Large Peptide

AbstractCavity creation is a key to the origin of biological functions. Small cavities such as enzyme pockets are created simply through liner peptide folding. Nature can create much larger cavities by threading and entangling large peptide rings, as learned from gigantic virus capsids, where not only chemical structures but the topology of threaded rings must be controlled. Although interlocked molecules are a topic of current interest, they have for decades been explored merely as elements of molecular machines, or as a synthetic challenge. No research has specifically targeted them for, and succesfully achieved, cavity creation. Here we report the emergence of a huge capsular framework via multiple threading of metal–peptide rings. Six equivalent C4-propeller-shaped rings, each consisting of four oligopeptides and Ag+, are threaded by each other a total of twelve times (crossing number: 24) to assemble into a well-defined 4 nm-sized sphere, which acts as a huge molecular capsule.

scholarly journals Beyond switches: Rotaxane- and catenane-based synthetic molecular motors

2008 ◽  
Vol 80 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Euan R. Kay ◽  
David A. Leigh
Keyword(s):  
Molecular Motors ◽  
Physical Science ◽  
Statistical Physics ◽  
Biological Process ◽  
Molecular Level ◽  
Molecular Machines ◽  
Interlocked Molecules ◽  
Recent Developments ◽  
New Generation ◽  
First Time

Nature uses molecular motors and machines in virtually every significant biological process, but learning how to design and assemble simpler artificial structures that function through controlled molecular-level motion is a major challenge for contemporary physical science. The established engineering principles of the macroscopic world can offer little more than inspiration to the molecular engineer who creates devices for an environment where everything is constantly moving and being buffeted by other atoms and molecules. Rather, experimental designs for working molecular machines must follow principles derived from chemical kinetics, thermodynamics, and nonequilibrium statistical physics. The remarkable characteristics of interlocked molecules make them particularly useful for investigating the control of motion at the molecular level. Yet, the vast majority of synthetic molecular machines studied to date are simple two-state switches. Here we outline recent developments from our laboratory that demonstrate more complex molecular machine functions. This new generation of synthetic molecular machines can move continuously and progressively away from equilibrium, and they may be considered true prototypical molecular motors. The examples discussed exemplify two, fundamentally different, "Brownian ratchet" mechanisms previously developed in theoretical statistical physics and realized experimentally in molecular-level devices for the first time in these systems.

scholarly journals A precise polyrotaxane synthesizer

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. 1247-1253 ◽  
Author(s):  
Yunyan Qiu ◽  
Bo Song ◽  
Cristian Pezzato ◽  
Dengke Shen ◽  
Wenqi Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Assembly Line ◽  
Molecular Machines ◽  
One Pot ◽  
Interlocked Molecules ◽  
Design And Synthesis ◽  
Redox Cycles

Mechanically interlocked molecules are likely candidates for the design and synthesis of artificial molecular machines. Although polyrotaxanes have already found niche applications in exotic materials with specialized mechanical properties, efficient synthetic protocols to produce them with precise numbers of rings encircling their polymer dumbbells are still lacking. We report the assembly line–like emergence of poly[n]rotaxanes with increasingly higher energies by harnessing artificial molecular pumps to deliver rings in pairs by cyclical redox-driven processes. This programmable strategy leads to the precise incorporation of two, four, six, eight, and 10 rings carrying 8+, 16+, 24+, 32+, and 40+ charges, respectively, onto hexacationic polymer dumbbells. This strategy depends precisely on the number of redox cycles applied chemically or electrochemically, in both stepwise and one-pot manners.

Sequencing of chondroitin sulfate oligosaccharides using a novel exolyase from a marine bacterium that degrades hyaluronan and chondroitin sulfate/dermatan sulfate

2017 ◽  
Vol 474 (22) ◽  
pp. 3831-3848 ◽  
Author(s):  
Wenshuang Wang ◽  
Xiaojuan Cai ◽  
Naihan Han ◽  
Wenjun Han ◽  
Kazuyuki Sugahara ◽  
...  
Keyword(s):  
Chondroitin Sulfate ◽  
Marine Bacterium ◽  
Dermatan Sulfate ◽  
Specific Activity ◽  
Structural Complexity ◽  
Complex Structures ◽  
Biological Functions ◽  
Chemical Structures ◽  
Lyase Activity ◽  
Sugar Chains

Glycosaminoglycans (GAGs) are a family of chemically heterogeneous polysaccharides that play important roles in physiological and pathological processes. Owing to the structural complexity of GAGs, their sophisticated chemical structures and biological functions have not been extensively studied. Lyases that cleave GAGs are important tools for structural analysis. Although various GAG lyases have been identified, exolytic lyases with unique enzymatic property are urgently needed for GAG sequencing. In the present study, a putative exolytic GAG lyase from a marine bacterium was recombinantly expressed and characterized in detail. Since it showed exolytic lyase activity toward hyaluronan (HA), chondroitin sulfate (CS), and dermatan sulfate (DS), it was designated as HCDLase. This novel exolyase exhibited the highest activity in Tris–HCl buffer (pH 7.0) at 30°C. Especially, it showed a specific activity that released 2-aminobenzamide (2-AB)-labeled disaccharides from the reducing end of 2-AB-labeled CS oligosaccharides, which suggest that HCDLase is not only a novel exolytic lyase that can split disaccharide residues from the reducing termini of sugar chains but also a useful tool for the sequencing of CS chains. Notably, HCDLase could not digest 2-AB-labeled oligosaccharides from HA, DS, or unsulfated chondroitin, which indicated that sulfates and bond types affect the catalytic activity of HCDLase. Finally, this enzyme combined with CSase ABC was successfully applied for the sequencing of several CS hexa- and octasaccharides with complex structures. The identification of HCDLase provides a useful tool for CS-related research and applications.

A Mechanically Planar Chiral Rotaxane Ligand for Enantioselective Catalysis

2019 ◽  
Author(s):  
Andrew Heard ◽  
Stephen Goldup
Keyword(s):  
Active Site ◽  
Molecular Machines ◽  
Enantioselective Catalysis ◽  
Interlocked Molecules ◽  
End Groups ◽  
Mechanical Bond

<p> <b>Rotaxanes are interlocked molecules in which a molecular ring is trapped on a dumbbell-shaped axle due to its inability to escape over the bulky end groups, resulting in a so-called mechanical bond. Interlocked molecules have mainly been studied as components of molecular machines, but the crowded, flexible environment created by threading one molecule through another, reminiscent of the active site of an enzyme, has also been explored in catalysis and sensing. However, so far the applications of one of the most intriguing properties of interlocked molecules, their ability to display stereogenic units that do not rely on the stereochemistry of their covalent subunits, termed "mechanical chirality", have yet to be properly explored and prototypical demonstration of the applications of mechanically chiral rotaxanes remain scarce. Here we describe a mechanically planar chiral rotaxane-based Au complex that mediates a cyclopropanation reaction with stereoselectivities that are comparable with conventional covalent catalyst reported for this reaction.</b></p>

scholarly journals [c2]Daisy Chain Rotaxanes as Molecular Muscles

CCS Chemistry ◽  
2019 ◽  
pp. 83-96 ◽  
Author(s):  
Antoine Antoine ◽  
Emilie Moulin ◽  
Gad Fuks ◽  
Nicolas Giuseppone
Keyword(s):  
Single Molecule ◽  
Soft Matter ◽  
Macroscopic Scale ◽  
Interlocked Molecules ◽  
Single Molecule Level ◽  
Chemical Structures ◽  
Internal Motions ◽  
Myosin Filaments ◽  
History Of ◽  
Physical Tools

Bistable [ c2]daisy chain rotaxanes represent a particularly intriguing class of interlocked molecules that can produce internal sliding movements with a net contraction or extension at the single-molecule level. These nanometric motions show some analogies with the sliding motions of actin and myosin filaments in sarcomeres, and this is why [ c2]daisy chain rotaxanes have been also named as “molecular muscles,” as their first synthesis in 2000. In this minireview, the authors discuss the recent history of these molecules, their modular chemical structures, and the various synthetic pathways described in the literature to access them. The authors also detail how their internal motions can be controlled and characterized by a number of chemical and physical tools. The authors finally show that their integration within polymers and materials can give access to synchronized motions and amplifications up to the macroscopic scale. Overall, the numerous examples that have been described in the literature to date demonstrate that this family of molecules has already strongly influenced the entire field of research on artificial molecular machines, and has the potential to be implemented as actuators working at all scales, from nanometric-switchable devices to mechanically active soft matter materials.

Plant Neoflavonoids: Chemical Structures and Biological Functions

2020 ◽  
pp. 35-57
Author(s):  
Padam Kumar ◽  
Tanveer Ahamad ◽  
Devendra Pratap Mishra ◽  
Mohammad Faheem Khan
Keyword(s):  
Biological Functions ◽  
Chemical Structures

A Mechanically Planar Chiral Rotaxane Ligand for Enantioselective Catalysis

2019 ◽  
Author(s):  
Andrew Heard ◽  
Stephen Goldup
Keyword(s):  
Active Site ◽  
Molecular Machines ◽  
Enantioselective Catalysis ◽  
Interlocked Molecules ◽  
End Groups ◽  
Mechanical Bond

<p> <b>Rotaxanes are interlocked molecules in which a molecular ring is trapped on a dumbbell-shaped axle due to its inability to escape over the bulky end groups, resulting in a so-called mechanical bond. Interlocked molecules have mainly been studied as components of molecular machines, but the crowded, flexible environment created by threading one molecule through another, reminiscent of the active site of an enzyme, has also been explored in catalysis and sensing. However, so far the applications of one of the most intriguing properties of interlocked molecules, their ability to display stereogenic units that do not rely on the stereochemistry of their covalent subunits, termed "mechanical chirality", have yet to be properly explored and prototypical demonstration of the applications of mechanically chiral rotaxanes remain scarce. Here we describe a mechanically planar chiral rotaxane-based Au complex that mediates a cyclopropanation reaction with stereoselectivities that are comparable with conventional covalent catalyst reported for this reaction.</b></p>

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