All‐Graphitic Multilaminate Mesoporous Membranes by Interlayer‐Confined Molecular Assembly

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

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Amphiphiles: Molecular Assembly and Applications

10.1021/bk-2011-1070 ◽

2011 ◽

Cited By ~ 7

Keyword(s):

Molecular Assembly

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Chemically Fueled Assembly of Macrocycles Comprising Multiple Transient Bonds

10.26434/chemrxiv.11426007.v1 ◽

2019 ◽

Author(s):

Mohammad Mosharraf Hossain ◽

Joshua Atkinson ◽

Scott Hartley

Keyword(s):

Covalent Bond ◽

Dicarboxylic Acids ◽

Molecular Assembly ◽

Chemical Systems ◽

Complex Architectures ◽

The Creation ◽

Dynamic Exchange

Dissipative (nonequilibrium) assembly powered by chemical fuels has great potential for the creation of new adaptive chemical systems. However, while molecular assembly at equilibrium is routinely used to prepare complex architectures from polyfunctional monomers, species formed out of equilibrium have, to this point, been structurally very simple. In most examples the fuel simply effects the formation of a single transient covalent bond. Here, we show that chemical fuels can assemble bifunctional components into macrocycles containing multiple transient bonds. Specifically, dicarboxylic acids give aqueous dianhydride macrocycles on treatment with a carbodiimide. The macrocycle is assembled efficiently as a consequence of both fuel-dependent and -independent mechanisms: it undergoes slower decomposition, building up as the fuel recycles the components, and is a favored product of the dynamic exchange of the anhydride bonds. These results create new possibilities for generating structurally sophisticated out-of-equilibrium species.

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Chemically Fueled Assembly of Macrocycles Comprising Multiple Transient Bonds

10.26434/chemrxiv.11426007 ◽

2019 ◽

Author(s):

Mohammad Mosharraf Hossain ◽

Joshua Atkinson ◽

Scott Hartley

Keyword(s):

Covalent Bond ◽

Dicarboxylic Acids ◽

Molecular Assembly ◽

Chemical Systems ◽

Complex Architectures ◽

The Creation ◽

Dynamic Exchange

Dissipative (nonequilibrium) assembly powered by chemical fuels has great potential for the creation of new adaptive chemical systems. However, while molecular assembly at equilibrium is routinely used to prepare complex architectures from polyfunctional monomers, species formed out of equilibrium have, to this point, been structurally very simple. In most examples the fuel simply effects the formation of a single transient covalent bond. Here, we show that chemical fuels can assemble bifunctional components into macrocycles containing multiple transient bonds. Specifically, dicarboxylic acids give aqueous dianhydride macrocycles on treatment with a carbodiimide. The macrocycle is assembled efficiently as a consequence of both fuel-dependent and -independent mechanisms: it undergoes slower decomposition, building up as the fuel recycles the components, and is a favored product of the dynamic exchange of the anhydride bonds. These results create new possibilities for generating structurally sophisticated out-of-equilibrium species.

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Multi-Stimuli-Responsive Mesoporous Membranes and Effect of Molecular Architecture on Thermo- and pH-Responsive Behavior of the grafted Block Copolymer brushes

10.26434/chemrxiv.7037699 ◽

2019 ◽

Author(s):

Yanchun Tang ◽

Kohzo Ito ◽

Hideaki Yokoyama

Keyword(s):

Polymer Brushes ◽

Diblock Copolymers ◽

Neutron Reflectivity ◽

Molecular Architecture ◽

Stimuli Responsive ◽

Responsive Polymer ◽

The Matrix ◽

Stable Part ◽

Copolymer Brushes ◽

Mesoporous Membranes

In this study, we prepared ultrafiltration membranes with a decoupled responses of filtration property to temperature and pH. The membrane preparation method was developed based on our previous work. We utilized methanol-supercritical carbon dioxide (methanol-scCO2) selective swelling method to introduce nanopores to block copolymers containing poly(diethylene glycol) methyl ether methacrylate (PMEO2MA), poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and polystyrene (PS) blocks. Formation of the mesoporous barrier layer with PS being the mechanically stable part of the matrix was driven by selective swelling of the PMEO2MA-b-PDMAEMA domains. Due to the selective swelling of PMEO2MA or PDMAEMA domains to introduce pores, the interior of the pores are covered with PMEO2MA or PDMAEMA blocks after pore formation. The PMEO2MA-b-PDMAEMA polymer brushes are naturally attached on the pore walls and worked as functional gates. PMEO2MA is a non-toxic, neutral thermo-responsive polymer with LCST at 26 ᴼC. PDMAEMA is a typical weak polyelectrolyte with pKa value at 7.0-7.5 and also a thermo-responsive polymer revealed a LCST of 20-80 °C in aqueous solution. Therefore, these membranes were expected to have multi dimensions as function of the combination of temperature and pH. Moreover, to understand the detail of the temperature and pH depended conformation transitions of PMEO2MA-b-PDMAEMA brushes, those diblock copolymers were end-tethered on flat substrates and analyzed via neutron reflectivity (NR).

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Structure of mouse Mx1 protein. Molecular assembly and GTP-dependent conformational change

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)82434-6 ◽

1993 ◽

Vol 268 (20) ◽

pp. 15033-15038

Author(s):

M. Nakayama ◽

K. Yazaki ◽

A. Kusano ◽

K. Nagata ◽

N. Hanai ◽

...

Keyword(s):

Conformational Change ◽

Molecular Assembly

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Identifying molecules as biosignatures with assembly theory and mass spectrometry

Nature Communications ◽

10.1038/s41467-021-23258-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Stuart M. Marshall ◽

Cole Mathis ◽

Emma Carrick ◽

Graham Keenan ◽

Geoffrey J. T. Cooper ◽

...

Keyword(s):

Mass Spectrometry ◽

De Novo ◽

Outer Space ◽

Molecular Assembly ◽

Detection Experiment ◽

Complex Molecules ◽

The World ◽

Life Detection ◽

Molecular Complexity ◽

The Universe

AbstractThe search for alien life is hard because we do not know what signatures are unique to life. We show why complex molecules found in high abundance are universal biosignatures and demonstrate the first intrinsic experimentally tractable measure of molecular complexity, called the molecular assembly index (MA). To do this we calculate the complexity of several million molecules and validate that their complexity can be experimentally determined by mass spectrometry. This approach allows us to identify molecular biosignatures from a set of diverse samples from around the world, outer space, and the laboratory, demonstrating it is possible to build a life detection experiment based on MA that could be deployed to extraterrestrial locations, and used as a complexity scale to quantify constraints needed to direct prebiotically plausible processes in the laboratory. Such an approach is vital for finding life elsewhere in the universe or creating de-novo life in the lab.

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SiC mesoporous membranes for sulfuric acid decomposition at high temperatures in the iodine–sulfur process

RSC Advances ◽

10.1039/d0ra06919a ◽

2020 ◽

Vol 10 (68) ◽

pp. 41883-41890

Author(s):

Xin Yu ◽

Qing Wang ◽

Hiroki Nagasawa ◽

Masakoto Kanezashi ◽

Toshinori Tsuru

Keyword(s):

Sulfuric Acid ◽

High Temperatures ◽

Membrane Reactor ◽

Acid Decomposition ◽

Sic Particles ◽

Sulfuric Acid Decomposition ◽

Mesoporous Membranes ◽

Mesoporous Membrane ◽

Reaction Equilibrium

In the present study, SiC particles derived mesoporous membrane was discovered and applied to membrane reactor for H2SO4 decomposition. The reaction equilibrium was moved the to the product side by membrane reactor with extraction at 600 °C.

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