Absolute Asymmetric Catalysis, from Concept to Experiment: A Narrative

Synlett ◽  
2021 ◽  
Author(s):  
Joaquim Crusats ◽  
Albert Moyano
Keyword(s):  
Asymmetric Catalysis ◽  
Self Assembly ◽  
Mirror Symmetry ◽  
Dissipative Structures ◽  
The Self ◽  
Supramolecular System ◽  
Alternative Mechanism ◽  
Experimental Realization ◽  
Molecular Systems ◽  
Catalytically Active

In order to explain the origin of the single-handedness of the molecules of life (biological homochirality), the appearence of an initial enantiomeric imbalance by spontaneous mirror-symmetry breaking (SMSB) in prebiotic reactions is usually assumed, but examples of its experimental realization are very scarce. SMSB in the self-assembly of achiral molecules is much more common, and the chirality sign of the resulting supramolecular system can be controlled by the action of macroscopic chiral forces. We have proposed a new mechanism for the generation of net chirality in molecular systems, in which the SMSB takes place in the formation of chiral supramolecular dissipative structures from achiral monomers, leading to asymmetric imbalances in their composition that are subsequently transferred to a standard enantioselective catalytic reaction, dodging in this way the highly limiting requirement of finding suitable reactions in solution that show enantioselective autocatalysis. We propose the name “absolute asymmetric catalysis” for this approach, in which an achiral monomer is converted to a nonracemic chiral aggregate that is generated with SMSB and that is catalytically active. We present in this Account a step-by-step narrative of the development of this prebiotically plausible, alternative mechanism for the emergence of net chirality in molecular reactions.

scholarly journals Release of proteins and enzymes from vesicular compartments by alternating magnetic fields

2015 ◽  
Vol 17 (24) ◽  
pp. 15579-15588 ◽  
Author(s):  
Andrew Booth ◽  
Inmaculada C. Pintre ◽  
Yue Lin ◽  
Julie E. Gough ◽  
Simon J. Webb
Keyword(s):  
Magnetic Fields ◽  
Magnetite Nanoparticles ◽  
Self Assembly ◽  
The Self ◽  
Catalytically Active ◽  
Alternating Magnetic Fields

The self-assembly of avidin, biotinylated vesicles and biotinylated (3-aminopropyl)triethoxysilane-coated magnetite nanoparticles gave a nanomaterial able to magnetically release catalytically active enzymes from vesicular compartments.

Tunable multi-color luminescence from a self-assembled cyanostilbene and cucurbit[7]uril in aqueous media

2020 ◽  
Vol 56 (4) ◽  
pp. 655-658 ◽  
Author(s):  
Shubhra Kanti Bhaumik ◽  
Supratim Banerjee
Keyword(s):  
Self Assembly ◽  
Aqueous Media ◽  
The Self ◽  
Supramolecular System ◽  
Self Assembled ◽  
Guest Chemistry

A tunable multicolor luminescent supramolecular system was designed in aqueous media employing the self-assembly of a cationic amphiphilic cyanostilbene and the host–guest chemistry of cucurbit[7]uril.

scholarly journals Symmetry Breaking in Self-Assembled Nanoassemblies

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 950 ◽  
Author(s):  
Yutao Sang ◽  
Minghua Liu
Keyword(s):  
Symmetry Breaking ◽  
Self Assembly ◽  
Mirror Symmetry ◽  
Covalent Bond ◽  
The Self ◽  
Control Methods ◽  
Supramolecular Chirality ◽  
Dispersed System ◽  
Chiral Materials ◽  
And Control

The origin of biological homochirality, e.g., life selects the L-amino acids and D-sugar as molecular component, still remains a big mystery. It is suggested that mirror symmetry breaking plays an important role. Recent researches show that symmetry breaking can also occur at a supramolecular level, where the non-covalent bond was crucial. In these systems, equal or unequal amount of the enantiomeric nanoassemblies could be formed from achiral molecules. In this paper, we presented a brief overview regarding the symmetry breaking from dispersed system to gels, solids, and at interfaces. Then we discuss the rational manipulation of supramolecular chirality on how to induce and control the homochirality in the self-assembly system. Those physical control methods, such as Viedma ripening, hydrodynamic macro- and micro-vortex, superchiral light, and the combination of these technologies, are specifically discussed. It is hoped that the symmetry breaking at a supramolecular level could provide useful insights into the understanding of natural homochirality and further designing as well as controlling of functional chiral materials.

A new supramolecular catalytic system: the self-assembly of Rh8 cage host anthracene molecules for [4 + 4] cycloaddition induced by UV irradiation

2020 ◽  
Vol 49 (28) ◽  
pp. 9688-9693
Author(s):  
Wei-Bin Yu ◽  
Feng-Yi Qiu ◽  
Po Sun ◽  
Hua-Tian Shi ◽  
Zhi-Feng Xin
Keyword(s):  
Uv Irradiation ◽  
Catalytic System ◽  
Self Assembly ◽  
Uv Light ◽  
Cycloaddition Reaction ◽  
Supramolecular Assembly ◽  
The Self ◽  
Supramolecular System ◽  
Guest Molecules ◽  
Guest Chemistry

The supramolecular assembly is significant in host–guest chemistry. In this work, a new supramolecular system assembled through a distorted cuboid was introduced. Moreover, the [4 + 4] cycloaddition reaction of the guest molecules was further studied under UV light.

scholarly journals Effect of [Zr(α-PW11O39)2]10− Polyoxometalate on the Self-Assembly of Surfactant Molecules in Water Studied by Fluorescence and DOSY NMR Spectroscopy

Inorganics ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 112 ◽  
Author(s):  
Thomas Quanten ◽  
Pavletta Shestakova ◽  
Aleksandar Kondinski ◽  
Tatjana Parac-Vogt
Keyword(s):  
Nmr Spectroscopy ◽  
Self Assembly ◽  
Aqueous Media ◽  
Sodium Dodecyl ◽  
Critical Micellar Concentration ◽  
The Self ◽  
Catalytically Active ◽  
Keggin Polyoxometalate ◽  
Kinetics Of ◽  
And Diffusion

The catalytic fragmentation of hydrophobic proteins by polyoxometalates (POMs) requires the presence of surfactants in order to increase the solubility of the protein. Depending on the nature of the surfactant, different effects on the kinetics of protein hydrolysis are observed. As the molecular interactions between the POMs and surfactants in solutions have been scarcely explored, in this study, the interaction between the catalytically active Keggin polyoxometalate [Zr(α-PW11O39)2]10− and four different surfactants—sodium dodecyl sulfate (SDS), dodecyldimethyl(3-sulfopropyl)ammonium (Zw3-12), dodecyldimethyl(3-sulfopropyl) ammonium (CHAPS), and polyethylene glycol tert-octylphenyl ether (TX-100)—have been studied in aqueous media. The effect of polyoxometalate on the self-assembly of surfactant molecules into micelles and on the critical micellar concentration (CMC) has been examined by fluorescence spectroscopy and diffusion ordered NMR spectroscopy (DOSY).

scholarly journals Catalytic Amyloids as Novel Synthetic Hydrolases

2021 ◽  
Vol 22 (17) ◽  
pp. 9166
Author(s):  
Eva Duran-Meza ◽  
Rodrigo Diaz-Espinoza
Keyword(s):  
Self Assembly ◽  
Polypeptide Chain ◽  
The Self ◽  
Attractive Alternative ◽  
Small Peptides ◽  
Pathological Conditions ◽  
Hydrolytic Activities ◽  
Different Types ◽  
Catalytically Active

Amyloids are supramolecular assemblies composed of polypeptides stabilized by an intermolecular beta-sheet core. These misfolded conformations have been traditionally associated with pathological conditions such as Alzheimer’s and Parkinson´s diseases. However, this classical paradigm has changed in the last decade since the discovery that the amyloid state represents a universal alternative fold accessible to virtually any polypeptide chain. Moreover, recent findings have demonstrated that the amyloid fold can serve as catalytic scaffolds, creating new opportunities for the design of novel active bionanomaterials. Here, we review the latest advances in this area, with particular emphasis on the design and development of catalytic amyloids that exhibit hydrolytic activities. To date, three different types of activities have been demonstrated: esterase, phosphoesterase and di-phosphohydrolase. These artificial hydrolases emerge upon the self-assembly of small peptides into amyloids, giving rise to catalytically active surfaces. The highly stable nature of the amyloid fold can provide an attractive alternative for the design of future synthetic hydrolases with diverse applications in the industry, such as the in situ decontamination of xenobiotics.

The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

1971 ◽  
Vol 29 ◽  
pp. 366-367
Author(s):  
M. Kessel ◽  
R. MacColl
Keyword(s):  
Self Assembly ◽  
Analytical Ultracentrifugation ◽  
Uranyl Acetate ◽  
The Self ◽  
Major Protein ◽  
Subunit Structure ◽  
Blue Green Alga ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

Interrelationship of the cellular distribution and secretion of regular structure (RS) protein in Bacillus licheniformis nm 105

1992 ◽  
Vol 50 (1) ◽  
pp. 712-713
Author(s):  
Xiaorong Zhu ◽  
Richard McVeigh ◽  
Bijan K. Ghosh
Keyword(s):  
Alkaline Phosphatase ◽  
Bacillus Licheniformis ◽  
Self Assembly ◽  
Gel Electrophoresis ◽  
Culture Supernatant ◽  
Regular Structure ◽  
The Self ◽  
Cellular Distribution ◽  
Structural Protein ◽  
Laboratory Cultures

A mutant of Bacillus licheniformis 749/C, NM 105 exhibits some notable properties, e.g., arrest of alkaline phosphatase secretion and overexpression and hypersecretion of RS protein. Although RS is known to be widely distributed in many microbes, it is rarely found, with a few exceptions, in laboratory cultures of microorganisms. RS protein is a structural protein and has the unusual properties to form aggregate. This characteristic may have been responsible for the self assembly of RS into regular tetragonal structures. Another uncommon characteristic of RS is that enhanced synthesis and secretion which occurs when the cells cease to grow. Assembled RS protein with a tetragonal structure is not seen inside cells at any stage of cell growth including cells in the stationary phase of growth. Gel electrophoresis of the culture supernatant shows a very large amount of RS protein in the stationary culture of the B. licheniformis. It seems, Therefore, that the RS protein is cotranslationally secreted and self assembled on the envelope surface.

Nanoscale Self-Assembly Using Ion and Electron Beam Techniques: A Rapid Review

MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho
Keyword(s):  
Electron Beam ◽  
Self Assembly ◽  
Ion Beam ◽  
Three Dimensional ◽  
The Self ◽  
Stress Generation ◽  
Rapid Review ◽  
High Yield ◽  
3D Nanostructures ◽  
Self Assembled

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.

Bottom-up Evolution from Disks to High-Genus Polymersomes

2018 ◽  
Author(s):  
Claudia Contini ◽  
Russell Pearson ◽  
Linge Wang ◽  
Lea Messager ◽  
Jens Gaitzsch ◽  
...  
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Amphiphilic Copolymers ◽  
Chain Entanglement ◽  
Bottom Up ◽  
New Approach ◽  
High Genus ◽  
Transmission Electron ◽  
Minimal Radius ◽  
Stop Flow

<div><div><div><p>We report the design of polymersomes using a bottom-up approach where the self-assembly of amphiphilic copolymers poly(2-(methacryloyloxy) ethyl phosphorylcholine)–poly(2-(diisopropylamino) ethyl methacrylate) (PMPC-PDPA) into membranes is tuned using pH and temperature. We study this process in detail using transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and stop-flow ab- sorbance disclosing the molecular and supramolecular anatomy of each structure observed. We report a clear evolution from disk micelles to vesicle to high-genus vesicles where each passage is controlled by pH switch or temperature. We show that the process can be rationalised adapting membrane physics theories disclosing important scaling principles that allow the estimation of the vesiculation minimal radius as well as chain entanglement and coupling. This allows us to propose a new approach to generate nanoscale vesicles with genus from 0 to 70 which have been very elusive and difficult to control so far.</p></div></div></div>

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