Chiral Helical Polymer Nanomaterials with Tunable Morphology: Prepared with Chiral Solvent To Induce Helix-Sense-Selective Precipitation Polymerization

2018 ◽  
Vol 51 (21) ◽  
pp. 8878-8886 ◽  
Author(s):  
Yingjie Zhang ◽  
Jianping Deng ◽  
Kai Pan
Keyword(s):  
Precipitation Polymerization ◽  
Selective Precipitation ◽  
Helical Polymer ◽  
Tunable Morphology

Electron Microscopy and image analysis of nucleo-protein complexes

1994 ◽  
Vol 52 ◽  
pp. 88-89
Author(s):  
E. H. Egelman ◽  
X. Yu
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Normal Cell ◽  
Genetic Recombination ◽  
Protein Complexes ◽  
Chromosomal Rearrangements ◽  
Reca Protein ◽  
E Coli ◽  
Helical Polymer ◽  
Specific Protease

The RecA protein of E. coli has been shown to mediate genetic recombination, regulate its own synthesis, control the expression of other genes, act as a specific protease, form a helical polymer and have an ATPase activity, among other observed properties. The unusual filament formed by the RecA protein on DNA has not previously been shown to exist outside of bacteria. Within this filament, the 36 Å pitch of B-form DNA is extended to about 95 Å, the pitch of the RecA helix. We have now establishedthat similar nucleo-protein complexes are formed by bacteriophage and yeast proteins, and availableevidence suggests that this structure is universal across all of biology, including humans. Thus, understanding the function of the RecA protein will reveal basic mechanisms, in existence inall organisms, that are at the foundation of general genetic recombination and repair.Recombination at this moment is assuming an importance far greater than just pure biology. The association between chromosomal rearrangements and neoplasms has become stronger and stronger, and these rearrangements are most likely products of the recombinatory apparatus of the normal cell. Further, damage to DNA appears to be a major cause of cancer.

SuFExable Polymers with Helical Structures Derived from Thionyl Tetrafluoride (SOF4)

2019 ◽  
Author(s):  
Suhua Li ◽  
Gencheng Li ◽  
Bing Gao ◽  
Sidharam P. Pujari ◽  
Xiaoyan Chen ◽  
...  
Keyword(s):  
Functional Polymers ◽  
Polymer Chains ◽  
New Materials ◽  
Helical Structures ◽  
Polymer Backbone ◽  
Silyl Ethers ◽  
Helical Polymer ◽  
Key Characteristics ◽  
Post Modification ◽  
Individual Polymer

The first SuFEx click chemistry synthesis of SOF<sub>4</sub>-derived copolymers based upon the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers) is described. This novel class of SuFEx polymer presents two key characteristics: First, the newly created [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and primed to undergo further high-yielding and precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate the presence of helical polymer structures, which itself suggests a preferential approach of new monomers onto the growing polymer chain upon the formation of the stereogenic linking moiety.

Extracellular polysaccharides from suspension cultures of Nicotiana plumbaginifolia

2020 ◽  
Author(s):  
Ian Sims ◽  
A Bacic
Keyword(s):  
Uronic Acid ◽  
Cell Suspension Cultures ◽  
Anion Exchange Chromatography ◽  
Nicotiana Plumbaginifolia ◽  
Suspension Cultures ◽  
Exchange Chromatography ◽  
Arabinogalactan Protein ◽  
Extracellular Polysaccharides ◽  
Selective Precipitation ◽  
The Individual

The soluble polymers secreted by cell-suspension cultures of Nicotiana plumbaginifolia contained 78% carbohydrate, 6% protein and 4% inorganic material. The extracellular polysaccharides were separated into three fractions by anion-exchange chromatography using a gradient of imidazole-HCl at pH 7 and the individual polysaccharides in each fraction were then isolated by selective precipitation and enzymic treatment. Monosaccharide and linkage compositions were determined for each polysaccharide after reduction of uronic acid residues and the degree of esterification of the various uronic acid residues in each polysaccharide was determined concurrently with the linkage types. Six components were identified: an arabinoxyloglucan (comprising 34% of the total polysaccharide) and a galactoglucomannan (15%) in the unbound neutral fraction, a type II arabinogalactan (an arabinogalactan-protein, 11%) and an acidic xylan (3%) in the first bound fraction, and an arabinoglucuronomannan (11%) and a galacturonan (26%) in the second bound fraction. © 1995.

scholarly journals Precipitation Polymerization: Precisely Controlled Microsphere Design via Visible‐Light Cross‐Linking of Functional Prepolymers (Adv. Funct. Mater. 26/2020)

2020 ◽  
Vol 30 (26) ◽  
pp. 2070173
Author(s):  
Jordan P. Hooker ◽  
Florian Feist ◽  
Laura Delafresnaye ◽  
Leonie Barner ◽  
Christopher Barner‐Kowollik
Keyword(s):  
Visible Light ◽  
Precipitation Polymerization ◽  
Cross Linking
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