Exquisite regulation of supramolecular equilibrium polymers in water: chain stoppers control length, polydispersity and viscoelasticity

2018 ◽  
Vol 9 (43) ◽  
pp. 5268-5277 ◽  
Author(s):  
Suneesh C. Karunakaran ◽  
Brian J. Cafferty ◽  
Miguel Peláez-Fernández ◽  
Kasahun Neselu ◽  
Ingeborg Schmidt-Krey ◽  
...  
Keyword(s):  
Cyanuric Acid ◽  
Supramolecular Polymers ◽  
Planar Surfaces ◽  
Water Chain ◽  
Equilibrium Polymers ◽  
Positively Charged

Positively charged molecules with planar surfaces control the length of supramolecular polymers formed by 2,4,6-triaminopyrimidine and a modified cyanuric acid.

scholarly journals Non-Equilibrium Generation of Catalytic Supramolecular Polymers of Pre-RNA Nucleobases

2021 ◽  
Author(s):  
Syed Pavel Afrose ◽  
Chiranjit Mahato ◽  
Pooja Sharma ◽  
Lisa Roy ◽  
Dibyendu Das
Keyword(s):  
Information Storage ◽  
Supramolecular Polymers ◽  
Polymer Backbone ◽  
Available Energy ◽  
Reversible Covalent ◽  
The Stability ◽  
Equilibrium Polymers ◽  
Emergence Of Life ◽  
Hydrolysis Of ◽  
Non Equilibrium

<p>Bioenergetics played critical roles for the chemical emergence of life where available energy resources drove the generation of primitive polymers and fueled early metabolism. Further, apart from information storage, the catalytic roles of primitive nucleic acid fragments have also been argued to be important for biopolymer evolution. Herein, we have demonstrated the non-equilibrium generation of catalytic supramolecular polymers of a possible proto-RNA building block (melamine) driven by a thermodynamically activated ester of low molecular weight. We utilized reversible covalent linkage to install a catalytic imidazole moiety in the polymer backbone. This resulted in energy dissipation via hydrolysis of the substrate predominantly from the assembled state and subsequent disassembly, thus installing kinetic asymmetry in the energy consumption cycle. Non-catalytic analogues led to kinetically stable polymers while inactivated substrates were unable to drive the polymerization. The non-equilibrium polymers of the pre-RNA bases were capable to spatiotemporally bind to a model cofactor. Notably, presence of an exogenous aromatic base augmented the stability of the polymers, reminiscent to what the molecular midwives did during early evolution. </p>

scholarly journals Non-Equilibrium Generation of Catalytic Supramolecular Polymers of Pre-RNA Nucleobases

2021 ◽  
Author(s):  
Syed Pavel Afrose ◽  
Chiranjit Mahato ◽  
Pooja Sharma ◽  
Lisa Roy ◽  
Dibyendu Das
Keyword(s):  
Information Storage ◽  
Supramolecular Polymers ◽  
Polymer Backbone ◽  
Available Energy ◽  
Reversible Covalent ◽  
The Stability ◽  
Equilibrium Polymers ◽  
Emergence Of Life ◽  
Hydrolysis Of ◽  
Non Equilibrium

<p>Bioenergetics played critical roles for the chemical emergence of life where available energy resources drove the generation of primitive polymers and fueled early metabolism. Further, apart from information storage, the catalytic roles of primitive nucleic acid fragments have also been argued to be important for biopolymer evolution. Herein, we have demonstrated the non-equilibrium generation of catalytic supramolecular polymers of a possible proto-RNA building block (melamine) driven by a thermodynamically activated ester of low molecular weight. We utilized reversible covalent linkage to install a catalytic imidazole moiety in the polymer backbone. This resulted in energy dissipation via hydrolysis of the substrate predominantly from the assembled state and subsequent disassembly, thus installing kinetic asymmetry in the energy consumption cycle. Non-catalytic analogues led to kinetically stable polymers while inactivated substrates were unable to drive the polymerization. The non-equilibrium polymers of the pre-RNA bases were capable to spatiotemporally bind to a model cofactor. Notably, presence of an exogenous aromatic base augmented the stability of the polymers, reminiscent to what the molecular midwives did during early evolution. </p>

Electrostatic Interaction between Dissimilarly Charged Membranes in Salt-Free Solution

2014 ◽  
Vol 590 ◽  
pp. 224-228
Author(s):  
Shih Hsiang Chang
Keyword(s):  
Electrostatic Interaction ◽  
Electric Double Layer ◽  
Surface Charge Density ◽  
Theoretical Study ◽  
Free Solution ◽  
Opposite Charge ◽  
Charge Densities ◽  
Planar Surfaces ◽  
Charged Membranes ◽  
Positively Charged

A theoretical study on the electrostatic interaction between the dissimilarly charged membranes in a salt-free solution has been presented in this paper. The results show that the electric double-layer force is always repulsive for positively charged planar surfaces regardless of surface charge density (or potential) and separation; however, a long-range attraction is observed between surfaces with unequally opposite charge densities. Such attractive force also exists and is independent of the separation when both surfaces carry unequally opposite potential.

Protamine-DNA interaction

1978 ◽  
Vol 36 (2) ◽  
pp. 200-201
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Small Volume ◽  
Double Helix ◽  
Dna Interaction ◽  
Dark Field ◽  
Sperm Head ◽  
Nuclear Proteins ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dna Double Helix ◽  
Positively Charged

Dark field electron microscopy has been used for the study of the structure of individual macromolecules with a resolution to at least the 5Å level. The use of this technique has been extended to the investigation of structure of interacting molecules, particularly the interaction between DNA and fish protamine, a class of basic nuclear proteins of molecular weight 4,000 daltons.Protamine, which is synthesized during spermatogenesis, binds to chromatin, displaces the somatic histones and wraps up the DNA to fit into the small volume of the sperm head. It has been proposed that protamine, existing as an extended polypeptide, winds around the minor groove of the DNA double helix, with protamine's positively-charged arginines lining up with the negatively-charged phosphates of DNA. However, viewing protamine as an extended protein is inconsistent with the results obtained in our laboratory.

Structure and Interaction of Protamine by Dark Field Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 160-161
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
3 Dimensional ◽  
Field Electron ◽  
Proposed Model ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Positively Charged

It has been shown for some time that it is possible to obtain images of small unstained proteins, with a resolution of approximately 5Å using dark field electron microscopy (1,2). Applying this technique, we have observed a uniformity in size and shape of the 2-dimensional images of pure specimens of fish protamines (salmon, herring (clupeine, Y-l) and rainbow trout (Salmo irideus)). On the basis of these images, a model for the 3-dimensional structure of the fish protamines has been proposed (2).The known amino acid sequences of fish protamines show stretches of positively charged arginines, separated by regions of neutral amino acids (3). The proposed model for protamine structure (2) consists of an irregular, right-handed helix with the segments of adjacent arginines forming the loops of the coil.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

Enhanced type I photoreaction of indocyanine green via electrostatic-force-driven aggregation

Nanoscale ◽  
2020 ◽  
Vol 12 (17) ◽  
pp. 9517-9523 ◽  
Author(s):  
Huizhen Fan ◽  
Yu Fan ◽  
Wenna Du ◽  
Rui Cai ◽  
Xinshuang Gao ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Indocyanine Green ◽  
Electrostatic Force ◽  
Type I ◽  
Positively Charged

ICG forms aggregates in positively charged mesoporous silica, which show an enhanced type I photoreaction pathway.

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

Crosslink Effects on Equilibrium Polymers

1995 ◽  
Vol 5 (4) ◽  
pp. 465-474 ◽  
Author(s):  
K. Elleuch ◽  
F. Lequeux ◽  
P. Pfeuty
Keyword(s):  
Equilibrium Polymers

Characteristics of the Interaction between Thrombin Exosite1 and the Sequence 269-297 of Platelet Glycoprotein Ibα

1998 ◽  
Vol 80 (08) ◽  
pp. 310-315 ◽  
Author(s):  
Marie-Christine Bouton ◽  
Christophe Thurieau ◽  
Marie-Claude Guillin ◽  
Martine Jandrot-Perrus
Keyword(s):  
Platelet Activation ◽  
Electrostatic Interactions ◽  
Platelet Glycoprotein ◽  
Thrombin Receptor ◽  
Central Position ◽  
Amidolytic Activity ◽  
N Terminus ◽  
Hydrolysis Of ◽  
Chemical Cross Linking ◽  
Positively Charged

SummaryThe interaction between GPIb and thrombin promotes platelet activation elicited via the hydrolysis of the thrombin receptor and involves structures located on the segment 238-290 within the N-terminal domain of GPIbα and the positively charged exosite 1 on thrombin. We have investigated the ability of peptides derived from the 269-287 sequence of GPIbα to interact with thrombin. Three peptides were synthesized, including Ibα 269-287 and two scrambled peptides R1 and R2 which are comparable to Ibα 269-287 with regards to their content and distribution of anionic residues. However, R2 differs from both Ibα 269-287 and R1 by the shifting of one proline from a central position to the N-terminus. By chemical cross-linking, we observed the formation of a complex between 125I-Ibα 269-287 and α-thrombin that was inhibited by hirudin, the C-terminal peptide of hirudin, sodium pyrophosphate but not by heparin. The complex did not form when γ-thrombin was substituted for α-thrombin. Ibα 269-287 produced only slight changes in thrombin amidolytic activity and inhibited thrombin binding to fibrin. R1 and R2 also formed complexes with α-thrombin, modified slightly its catalytic activity and inhibited its binding to fibrin. Peptides Ibα 269-287 and R1 inhibited platelet aggregation and secretion induced by low thrombin concentrations whereas R2 was without effect. Our results indicate that Ibα 269-287 interacts with thrombin exosite 1 via mainly electrostatic interactions, which explains why the scrambled peptides also interact with exosite 1. Nevertheless, the lack of effect of R2 on thrombin-induced platelet activation suggests that proline 280 is important for thrombin interaction with GPIb.

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