scholarly journals The influence of pressure on the self-assembly of the thick filament from the myosin of vertebrate skeletal muscle

1981 ◽  
Vol 197 (2) ◽  
pp. 301-308 ◽  
Author(s):  
J S Davis
Keyword(s):  
Hydrostatic Pressure ◽  
Self Assembly ◽  
Length Distribution ◽  
Thick Filament ◽  
The Self ◽  
Fine Tuning ◽  
Regulation Mechanism ◽  
Filament Assembly ◽  
Length Regulation ◽  
Definition Of

The thick-filament-monomeric-myosin equilibrium was prepared from pure myosin at pH 8.1. The application of hydrostatic pressure to the self-assembly equilibrium resulted in a biphasic dissociation curve in which a linear decrease in turbidity (a measure of weight added to or lost from the filament) was followed by a transition to a second pressure-insensitive phase. The first phase represents the effect of hydrostatic pressure on the growth or propagation phase of filament assembly. Here is was shown that hydrostatic pressure served to shorten the filaments in concert towards the bare zone whilst maintaining the narrow length distribution seen at atmospheric pressure; the filament concentration remained constant during the experiment. A more precise definition of the delta-v for the assembly of monomer into filament was obtained than had hitherto been possible. The positioning of the bare zone at the centre of the filament seems to be one of the more obvious functions of the length-regulation mechanism. It also appears that all the basic structural elements of the native thick filament are potentially present in the pH 8.1 homopolymer; its length can be increased by physiological concentrations of MgCl2 and decreased by pressure. The monodisperse native filament could then be formed by a fine tuning of the basic length-regulation mechanism of the homopolymer by the co-polymerization of the other thick-filament proteins.

scholarly journals Pressure-jump studies on the length-regulation kinetics of the self-assembly of myosin from vertebrate skeletal muscle into thick filament

1981 ◽  
Vol 197 (2) ◽  
pp. 309-314 ◽  
Author(s):  
J S Davis
Keyword(s):  
Self Assembly ◽  
Thick Filament ◽  
Dissociation Rate ◽  
The Self ◽  
Pressure Jump ◽  
Fixed Rate ◽  
Length Regulation ◽  
Kinetics Of ◽  
Step Mechanism ◽  
Vertebrate Skeletal Muscle

The self-assembly of myosin monomer into thick filament occurs via a two-step mechanism. At first a pair of myosin monomers reacts to form a parallel dimer; the dimer in turn adds to the filament ends at a rate that is independent of filament length. The rate of the dissociation reaction on the other hand is length-dependent. The ‘off’ rate constant has been shown to increase exponentially by a factor of 500 as the filament grows from the bare-zone out to its full length. The length of the filament is thus kinetically controlled; myosin is added to the filament at a fixed rate, whereas the dissociation rate increases to a point where equilibrium is established and the filament ceases to grow. The structural implications implicit in the mechanism are discussed.

Fine-tuning the Relationship between Religion and Intellectual Humility

2018 ◽  
Vol 46 (4) ◽  
pp. 305-314 ◽  
Author(s):  
Everett L. Worthington
Keyword(s):  
Religious Belief ◽  
The Self ◽  
Content Area ◽  
Fine Tuning ◽  
Epistemic Status ◽  
Intellectual Humility ◽  
The Core ◽  
Definition Of ◽  
Meaning System ◽  
The Relationship

I examine religious humility, which is one content area of intellectual humility. Intellectual humility is the subtype of humility that involves taking a humble stance in sharing ideas, especially when one is challenged or when an idea is threatening. I position religious humility within the context of general humility, spiritual humility, and relational humility, and thus arrive at several propositions. People who are intensely spiritually humble can hold dogmatic beliefs and believe themselves to be religiously humble, yet be perceived by others of different persuasions as religiously dogmatic and even arrogant. For such people to be truly religiously humble, they must feel that the religious belief is core to their meaning system. This requires discernment of which of the person’s beliefs are truly at the core. But also the religiously humble person must fulfill the definition of general humility, accurately perceiving the strengths and limitations of the self, being teachable to correct weaknesses, presenting oneself modestly, and being positively other-oriented. Humility thus involves (1) beliefs, values, and attitudes and (2) an interpersonal presentational style. Therefore, intellectually humble people must track the positive epistemic status of their beliefs and also must present with convicted civility.

scholarly journals Deciphering Molecular Self-Assembly through Electron Microscopy and Fluorescence Correlation Spectroscopy

2020 ◽  
Author(s):  
Subhankar Kundu ◽  
Arkaprava Chowdhury, ◽  
Somen Nandi ◽  
Kankan Bhattacharyya ◽  
Abhijit Patra
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
The Self ◽  
Fine Tuning ◽  
Assembly Process ◽  
Molecular Aggregates ◽  
Fluorescence Correlation ◽  
Self Assembled

Supramolecular self-assembly of small organic molecules has emerged as a powerful tool to construct well-defined micro- and nanoarchitecture through fine-tuning a range of intermolecular interactions. The size, shape, and optical properties of these nanostructures largely depend on the temperature and polarity of the medium, along with the specific self-assembled pattern of molecular building units. The engineering of supramolecular self-assembled nanostructures with morphology-dependent tunable emission is in high demand due to the promising scope in nanodevices and molecular machines. However, challenges are probing the evolution of molecular aggregates from a true solution and directing the self-assembly process in a pre-defined fashion. The structure of molecular aggregates in the solution can be predicted from fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) analysis. On the other hand, the morphology of the aggregates can also be visualized through electron microscopy. Nevertheless, a direct correlation between emission from molecular aggregates in the aqueous dispersion and their morphology obtained through a solid-state characterization is missing. In the present study, we decipher the sequential evolution of molecular nanofibers from solution to spherical and oblong-shaped nanoparticles through the variation of solvent polarity, adjusting the <a>hydrophobic-hydrophilic interactions</a>. The intriguing case of molecular self-assembly is elucidated employing a newly designed π-conjugated thiophene derivative (TPAn) through a combination of steady-state absorption, emission measurements, FCS, and electron microscopy. The FCS analysis and microscopy results infer that small-sized nanofibers in the dispersion are further agglomerated, resulting in a network of nanofibers upon solvent evaporation. <a>The evolution of organic nanofibers and subtle control over the self-assembly process demonstrated in the current investigation provides a general paradigm to correlate the size, shape, and emission properties of diverse fluorescent molecular aggregates in complex heterogeneous media, including a human cell. </a>

scholarly journals The myosin dimer: an intermediate in the self-assembly of the thick filament of vertebrate skeletal muscle

FEBS Letters ◽  
1982 ◽  
Vol 140 (2) ◽  
pp. 293-297 ◽  
Author(s):  
Julien S. Davis ◽  
Jennifer Buck ◽  
Elizabeth P. Greene
Keyword(s):  
Skeletal Muscle ◽  
Self Assembly ◽  
Thick Filament ◽  
The Self ◽  
Vertebrate Skeletal Muscle

scholarly journals New Insights on the Self-Assembly of Bio-sourced Block Copolymer MH-b-PS in Aqueous Solutions: Nanocorals, Cubosomes & Nanocubes

2021 ◽  
Author(s):  
Yomen Atassi ◽  
Redouane Borsali
Keyword(s):  
Aqueous Solution ◽  
Block Copolymer ◽  
Aqueous Solutions ◽  
Self Assembly ◽  
Room Temperature ◽  
Linear Structure ◽  
The Self ◽  
Fine Tuning ◽  
Experimental Parameters ◽  
First Time

Polymer self-assembly in solution still constitutes a simple methodology for the preparation of elegant yet sophisticated nanomaterials. This work aims at presenting how the fine tuning of the experimental parameters of the nanoprecipitation process can lead to a variety of novel morphologies ranging from nanocorals through cubosomes to nanocubes. A carbohydrate dibloc copolymer with a simple and linear structure MH1.2k-b-PS2.3 has been used as a model to illustrate the formation of these new self-assemblies. This is the first time that nanocube morphology has been generated using this type of bio-sourced co-polymer in aqueous solution and at room temperature.

scholarly journals Deciphering Molecular Self-Assembly through Electron Microscopy and Fluorescence Correlation Spectroscopy

2020 ◽  
Author(s):  
Subhankar Kundu ◽  
Arkaprava Chowdhury, ◽  
Somen Nandi ◽  
Kankan Bhattacharyya ◽  
Abhijit Patra
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
The Self ◽  
Fine Tuning ◽  
Assembly Process ◽  
Molecular Aggregates ◽  
Fluorescence Correlation ◽  
Self Assembled

Supramolecular self-assembly of small organic molecules has emerged as a powerful tool to construct well-defined micro- and nanoarchitecture through fine-tuning a range of intermolecular interactions. The size, shape, and optical properties of these nanostructures largely depend on the temperature and polarity of the medium, along with the specific self-assembled pattern of molecular building units. The engineering of supramolecular self-assembled nanostructures with morphology-dependent tunable emission is in high demand due to the promising scope in nanodevices and molecular machines. However, challenges are probing the evolution of molecular aggregates from a true solution and directing the self-assembly process in a pre-defined fashion. The structure of molecular aggregates in the solution can be predicted from fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) analysis. On the other hand, the morphology of the aggregates can also be visualized through electron microscopy. Nevertheless, a direct correlation between emission from molecular aggregates in the aqueous dispersion and their morphology obtained through a solid-state characterization is missing. In the present study, we decipher the sequential evolution of molecular nanofibers from solution to spherical and oblong-shaped nanoparticles through the variation of solvent polarity, adjusting the <a>hydrophobic-hydrophilic interactions</a>. The intriguing case of molecular self-assembly is elucidated employing a newly designed π-conjugated thiophene derivative (TPAn) through a combination of steady-state absorption, emission measurements, FCS, and electron microscopy. The FCS analysis and microscopy results infer that small-sized nanofibers in the dispersion are further agglomerated, resulting in a network of nanofibers upon solvent evaporation. <a>The evolution of organic nanofibers and subtle control over the self-assembly process demonstrated in the current investigation provides a general paradigm to correlate the size, shape, and emission properties of diverse fluorescent molecular aggregates in complex heterogeneous media, including a human cell. </a>

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.

Investigation of Au SAMs Photoclick Derivatization by PM-IRRAS

2019 ◽  
Author(s):  
Mark Workentin ◽  
François Lagugné-Labarthet ◽  
Sidney Legge
Keyword(s):  
Cell Adhesion ◽  
Self Assembly ◽  
Materials Science ◽  
Fibroblast Cell ◽  
Fine Tuning ◽  
Chemical System ◽  
Infrared Reflection ◽  
Assembled Monolayers ◽  
One Step ◽  
High Degree

In this work we present a clean one-step process for modifying headgroups of self-assembled monolayers (SAMs) on gold using photo-enabled click chemistry. A thiolated, cyclopropenone-caged strained alkyne precursor was first functionalized onto a flat gold substrate through self-assembly. Exposure of the cyclopropenone SAM to UV-A light initiated the efficient photochemical decarbonylation of the cyclopropenone moiety, revealing the strained alkyne capable of undergoing the interfacial strain-promoted alkyne-azide cycloaddition (SPAAC). Irradiated SAMs were derivatized with a series of model azides with varied hydrophobicity to demonstrate the generality of this chemical system for the modification and fine-tuning of the surface chemistry on gold substrates. SAMs were characterized at each step with polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to confirm successful functionalization and reactivity. Furthermore, to showcase the compatibility of this approach with biochemical applications, cyclopropenone SAMs were irradiated and modified with azide-bearing cell adhesion peptides to promote human fibroblast cell adhesion, then imaged by live cell fluorescence microscopy. Thus, the “photoclick” methodology reported here represents an improved, versatile, catalyst-free protocol that allows for a high degree of control over the modification of material surfaces, with applicability in materials science as well as biochemistry.<br>

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