α-Hemolysin: A Self-Assembling Protein Pore With Potential Applications In The Synthesis of New Materials

1991 ◽  
Vol 255 ◽  
Author(s):  
Hagan Bayley ◽  
Musti Krishnasastry ◽  
Barbara Walker ◽  
John Kasianowicz
Keyword(s):  
Genetic Manipulation ◽  
Internal Diameter ◽  
New Materials ◽  
Membrane Pores ◽  
Self Assembling ◽  
Assembly Mechanism ◽  
Potential Applications ◽  
Membrane Bound ◽  
Insight Into ◽  
Selection Of

AbstractA selection of nanoscale membrane pores is being constructed by genetic manipulation of α-hemolysin (αHL), a 33.2 kDa polypeptide secreted by the bacterium Staphylococcus aureus, which can self-assemble into hexameric cylindrical channels -1 to 2 nm In Internal diameter. Ultimately, the new pores will be used to confer novel permeability properties upon materials such as thin films utilizing, for example, monolayer sheets of the hexamer. Recombinant αHL (r-αHL) has now been obtained in multimilligram amounts and purified to homogeneity after overexpression of the αHL gene in Escherichia coli. The properties of r-αHL are closely similar to those of αHL purified from S. aureus. Recent deletion mutagenesis experiments have given us new insight into the assembly mechanism of the pore. Three intermediates have been identified: a membrane-bound monomer; an oligomeric pore precursor; and the hexameric pore itself. Currently, point mutogenesis combined with chemical modification is being used to produce new pores of different internal diameter, with selectivity for the passage of molecules and Ions, and with gating properties (the ability to open and close in response to a physical stimulus, e.g. an electric field or light).

Assembly of α-Hemolysin: a Proteinaceous Pore with Potential Applications in Materials Synthesis

1992 ◽  
Vol 292 ◽  
Author(s):  
Hagan Bayley ◽  
Musti Krishnasastry ◽  
Barbara Walker ◽  
John Kasianowicz
Keyword(s):  
Lipid Bilayers ◽  
Three Dimensional ◽  
Structural Data ◽  
Membrane Receptors ◽  
Internal Diameter ◽  
Amino Acid Residues ◽  
Materials Synthesis ◽  
Assembly Mechanism ◽  
Potential Applications ◽  
Membrane Bound

Abstractα-Hemolysin (αHL) is secreted by the bacteriumStaphylococcus aureusas a watersoluble polypeptide of 293 amino acid residues. When presented with lipid bilayers or the detergent deoxycholate (DOC), aHL assembles into hexameric cylindrical pores that each contain one channel ∼ 1 to 2 nm in Internal diameter. A long-term goal of this laboratory is to use wild-type or re-engineered αHL pores as components of nanoscale materials: for example, to confer novel permeability properties upon thin films. The implementation of this concept would be facilitated by a better understanding of the mechanism by which the pore assembles. Reviewed here are findings that have given us insight Into the assembly mechanism, including the results of recent mutagenesis experiments. A critical summary is given of knowledge about the conformation of the monomer In solution, the hexamerIc pore and two proposed intermediates in assembly (a membrane-bound monomer and an oligomeric pore precursor). Future directions are outlined Including the prospects of obtaining three-dimensional structural data on the αHL pore or its precursors, methods for obtaining better monolayer sheets and new experiments on the topography of the pore and its precursors. The role of membrane receptors in facilitating the assembly of αHL is also discussed. Finally, it is demonstrated that despite our rather rudimentary knowledge of the assembly process, the Information gained so far still allows the design of mutant (αHL polypeptides with useful properties. For example, αHL mutants whose pore-forming ability is activated by proteases have been made.

scholarly journals Allosteric pathway selection in templated assembly

2019 ◽  
Vol 5 (10) ◽  
pp. eaaw3353 ◽  
Author(s):  
Martijn van Galen ◽  
Ruben Higler ◽  
Joris Sprakel
Keyword(s):  
Building Blocks ◽  
Supramolecular Interactions ◽  
High Fidelity ◽  
Self Assembling ◽  
Molecular Building Blocks ◽  
Large Numbers ◽  
Solution Aggregation ◽  
Allosteric Pathway ◽  
Insight Into ◽  
Selection Of

Assembling large numbers of molecular building blocks into functional nanostructures is no trivial task. It relies on guiding building blocks through complex energy landscapes shaped by synergistic and antagonistic supramolecular interactions. In nature, the use of molecular templates is a potent strategy to navigate the process to the desired structure with high fidelity. Yet, nature’s templating strategy remains to be fully exploited in man-made nanomaterials. Designing effective template-guided self-assembling systems can only be realized through precise insight into how the chemical design of building blocks and the resulting balance of repulsive and attractive forces give rise to pathway selection and suppression of trapped states. We develop a minimal model to unravel the kinetic pathways and pathway selection of the templated assembly of molecular building blocks on a template. We show how allosteric activation of the associative interactions can suppress undesired solution-aggregation pathways and gives rise to a true template-assembly path.

An Insight into Oligopeptide Transporter 3 (OPT3) family proteins

2020 ◽  
Vol 27 ◽  
Author(s):  
Fırat Kurt
Keyword(s):  
Stress Responses ◽  
Chelating Agent ◽  
Biological Processes ◽  
Biotic And Abiotic Stress ◽  
Oligopeptide Transporter ◽  
Binding Residues ◽  
Fe Homeostasis ◽  
Proteins Interactions ◽  
Insight Into ◽  
Selection Of

: Oligopeptide transporter 3 (OPT3) proteins are one of the subsets of OPT clade, yet little is known about these transporters. Therefore, homolog OPT3 proteins in several plant species were investigated and characterized using bioinformatical tools. Motif and co-expression analyses showed that OPT3 proteins may be involved in both biotic and abiotic stress responses as well as growth and developmental processes. AtOPT3 usually seemed to take part in Fe homeostasis whereas ZmOPT3 putatively interacted with proteins involved in various biological processes from plant defense system to stress responses. Glutathione (GSH), as a putative alternative chelating agent, was used in the AtOPT3 and ZmOPT3 docking analyses to identify their putative binding residues. The information given in this study will contribute to the understanding of OPT3 proteins’ interactions in various pathways and to the selection of potential ligands for OPT3s.

Short Review and opinion: New matter properties and applications based on Hybrids Graphene based Metamaterials

2020 ◽  
Vol 04 ◽  
Author(s):  
A. Guillermo Bracamonte
Keyword(s):  
Short Review ◽  
New Materials ◽  
Design And Synthesis ◽  
Chemical Structures ◽  
Current State ◽  
Potential Applications ◽  
Fundamental Research ◽  
Miniaturized Instrumentation ◽  
And Control ◽  
Conductive Properties

: Graphene as Organic material showed special attention due to their electronic and conductive properties. Moreover, its highly conjugated chemical structures and relative easy modification permitted varied design and control of targeted properties and applications. In addition, this Nanomaterial accompanied with pseudo Electromagnetic fields permitted photonics, electronics and Quantum interactions with their surrounding that generated new materials properties. In this context, this short Review, intends to discuss many of these studies related with new materials based on graphene for light and electronic interactions, conductions, and new modes of non-classical light generation. It should be highlighted that these new materials and metamaterials are currently in progress. For this reason it was showed and discussed some representative examples from Fundamental Research with Potential Applications as well as for their incorporations to real Advanced devices and miniaturized instrumentation. In this way, it was proposed this Special issue entitled “Design and synthesis of Hybrids Graphene based Metamaterials”, in order to open and share the knowledge of the Current State of the Art in this Multidisciplinary field.

scholarly journals Structural analysis of cross α-helical nanotubes provides insight into the designability of filamentous peptide nanomaterials

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fengbin Wang ◽  
Ordy Gnewou ◽  
Charles Modlin ◽  
Leticia C. Beltran ◽  
Chunfu Xu ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Synthetic Peptide ◽  
Quaternary Structure ◽  
De Novo ◽  
Rational Approach ◽  
Lateral Interactions ◽  
Protein Assemblies ◽  
Self Assembling ◽  
Arginine Residues ◽  
Insight Into

AbstractThe exquisite structure-function correlations observed in filamentous protein assemblies provide a paradigm for the design of synthetic peptide-based nanomaterials. However, the plasticity of quaternary structure in sequence-space and the lability of helical symmetry present significant challenges to the de novo design and structural analysis of such filaments. Here, we describe a rational approach to design self-assembling peptide nanotubes based on controlling lateral interactions between protofilaments having an unusual cross-α supramolecular architecture. Near-atomic resolution cryo-EM structural analysis of seven designed nanotubes provides insight into the designability of interfaces within these synthetic peptide assemblies and identifies a non-native structural interaction based on a pair of arginine residues. This arginine clasp motif can robustly mediate cohesive interactions between protofilaments within the cross-α nanotubes. The structure of the resultant assemblies can be controlled through the sequence and length of the peptide subunits, which generates synthetic peptide filaments of similar dimensions to flagella and pili.

Exact analysis of the bending of wide beams by a modified elastica approach

2011 ◽  
Vol 225 (11) ◽  
pp. 2759-2764 ◽  
Author(s):  
L F Campanile ◽  
R Jähne ◽  
A Hasse
Keyword(s):  
Finite Element ◽  
Substantial Reduction ◽  
Short Review ◽  
Computational Effort ◽  
Two Dimensional ◽  
Finite Element Calculations ◽  
Dimensional Finite Element ◽  
Wide Beams ◽  
Insight Into ◽  
Selection Of

Classical beam models do not account for partial restraint of anticlastic bending and are therefore inherently inaccurate. This article proposes a modification of the exact Bernoulli–Euler equation which allows for an exact prediction of the beam's deflection without the need of two-dimensional finite element calculations. This approach offers a substantial reduction in the computational effort, especially when coupled with a fast-solving schema like the circle-arc method. Besides the description of the new method and its validation, this article offers an insight into the somewhat disregarded topic of anticlastic bending by a short review of the published theories and a selection of representative numerical results.

scholarly journals Lanthanide Homobimetallic Triple-Stranded Helicates: Insight into the Self-Assembly Mechanism

2004 ◽  
Vol 2004 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Mourad Elhabiri ◽  
Josef Hamacek ◽  
Jean-Claude G. Bünzli ◽  
Anne-Marie Albrecht-Gary
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Assembly Mechanism ◽  
Insight Into

Design and topological optimization of rear pressure bulkhead for a typical aircraft

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marshal Thakran ◽  
Meenakshi ◽  
Jitender Sharma ◽  
Charles Gilbert Martin
Keyword(s):  
Numerical Analysis ◽  
Significant Influence ◽  
Design Methodology ◽  
Structural Integrity ◽  
Topological Optimization ◽  
Content Type ◽  
Iterative Design ◽  
Practical Implications ◽  
Insight Into ◽  
Selection Of

Purpose The purpose of this paper is to evaluate the model of a rear pressure bulkhead with different design optimizations to meet the pressurized cabin requirements of an aircraft. Design/methodology/approach This paper presents the results of the static analysis of a dome-shaped rear pressure bulkhead model designed in Catia-v5. Numerical analysis of model meshed in hyper-mesh and solved using Opti-Struct for iterative design optimizations. Findings All the iterative models are analyzed at 9 Psi. Rear pressure bulkhead designed with L-section stringer shows better results than the model optimized with T-section stringer for the same thickness. The model optimized with L-shaped stinger also reduces the weight of the bulkhead without affecting the structural integrity. Practical implications It has been concluded in this paper that the selection of specific shapes of the stringers shows a significant influence on weight reduction. Originality/value This paper provides a topical, technical insight into the design and development of a rear pressure bulkhead. It also outlines the future development of dome-shaped rear pressure bulkhead.

Paradata in Documentation Standards and Recommendations for Digital Archaeological Visualisations

2020 ◽  
Vol 6 (2) ◽  
pp. 191-220
Author(s):  
Lisa Börjesson ◽  
Olle Sköld ◽  
Isto Huvila
Keyword(s):  
Research Data ◽  
Data Reuse ◽  
Lack Of Information ◽  
National Heritage ◽  
Processing History ◽  
International Harmonisation ◽  
Insight Into ◽  
Current Standards ◽  
Selection Of ◽  
As If

Abstract Digitalisation of research data and massive efforts to make it findable, accessible, interoperable, and reusable has revealed that in addition to an eventual lack of description of the data itself (metadata), data reuse is often obstructed by the lack of information about the datamaking and interpretation (i.e. paradata). In search of the extent and composition of categories for describing processes, this article reviews a selection of standards and recommendations frequently referred to as useful for documenting archaeological visualisations. It provides insight into 1) how current standards can be employed to document provenance and processing history (i.e. paradata), and 2) what aspects of the processing history can be made transparent using current standards and which aspects are pushed back or hidden. The findings show that processes are often either completely absent or only partially addressed in the standards. However, instead of criticising standards for bias and omissions as if a perfect description of everything would be attainable, the findings point to the need for a comprehensive consideration of the space a standard is operating in (e.g. national heritage administration or international harmonisation of data). When a standard is used in a specific space it makes particular processes, methods, or tools transparent. Given these premises, if the standard helps to document what needs to be documented (e.g. paradata), and if it provides a type of transparency required in a certain space, it is reasonable to deem the standard good enough for that purpose.

Uralsky, M. (2019). Mark Aldanov. A writer, a public figure and a gentleman of Russian emigration. Prefaced by S. Pesterev and S. Garciano. St. Petersburg: Aleteya. (In Russ.)

2021 ◽  
pp. 296-301
Author(s):  
V. V. Shadursky
Keyword(s):  
Childhood And Adolescence ◽  
Literary Critic ◽  
New Materials ◽  
Scholarly Research ◽  
Public Figure ◽  
Biographical Account ◽  
Moral Beauty ◽  
Selection Of

This first biographical account of M. Aldanov was authored by M. Uralsky, a writer of documentary prose. While not a strict academic publication, the book shows a thorough approach to selection of the material and verification of facts and introduces hitherto unknown documents, thus qualifying as a compelling piece of scholarly research. The book’s three parts are dedicated to key periods of Aldanov’s life: ‘A young Aldanov — happy years’ (1886–1917), ‘A historical novelist of Russian emigration’ (1919–1940), and ‘The twilight of life and work’ (1947–1957). Uralsky uncovered a number of new materials relating to Aldanov’s childhood and adolescence and his work in emigration, completing a reconstruction of the writer’s life. The biographer examines Aldanov’s personality as an artist, a literary critic, a journalist and a scholar. The book’s leitmotif is to actualise Aldanov’s idea of writers dedicating themselves to kalokagathia — the ‘moral beauty.’

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