scholarly journals Sulfated Alkyl Glucopyranans with Potent Antiviral Activity Synthesized by Ring-Opening Copolymerization of Anhydroglucose and Alkyl Anhydroglucose Monomers

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shiming Bai ◽  
Davaanyam Budragchaa ◽  
Shuqin Han ◽  
Taisei Kanamoto ◽  
Hideki Nakashima ◽  
...  
Keyword(s):  
Ring Opening ◽  
Model Compound ◽  
Dissociation Rate ◽  
Water Soluble ◽  
Sulfated Polysaccharides ◽  
High Association ◽  
Molecular Weights ◽  
Alkyl Groups ◽  
Dissociation Rate Constants ◽  
Anti Hiv

Sulfated glucopyranans having long alkyl groups were prepared by the ring-opening copolymerization of benzylated 1,6-anhydroglucopyranose with 3-O-octadecyl 1,6-anhydro-β-d-glucopyranose monomers, and subsequent deprotection and sulfation. Water-soluble sulfated glucopyranans with 2.8 and 4.7 mol% of 3-O-octadecyl group and lower molecular weights ofM-n= 2.5 × 103–5.1 × 103have potent anti-HIV activity at 0.05–1.25 μg/mL, even though sulfated polysaccharides with molecular weights belowM-n= 6 × 103had low anti-HIV activity. The interaction with poly-l-lysine as a model compound of proteins was analyzed by SPR, DSL, and zeta potential, indicating that the sulfated 3-O-octadecyl glucopyranans had high association and low dissociation rate constants, and the particle size increased after addition of poly-l-lysine. The anti-HIV activity was induced by electrostatic interaction between sulfate groups and amino groups of poly-l-lysine and by the synergistic effect of the hydrophobic long alkyl chain and hydrophilic sulfated group.

scholarly journals Biodegradable polysarcosine with inserted alanine residues: Synthesis and enzymolysis

2021 ◽  
Author(s):  
Peng Zhou ◽  
Jun Ling
Keyword(s):  
Ring Opening ◽  
Water Solubility ◽  
Water Soluble ◽  
Random Copolymers ◽  
Biodegradation Rate ◽  
Pancreatic Elastase ◽  
Molecular Weights ◽  
Mild Conditions ◽  
Protective Shield ◽  
The One

Polysarcosine (PSar), a water-soluble polypeptoid, is gifted with biodegradability via random ring-opening copolymerization of sarcosine- and alanine-N-thiocarboxyanhydrides catalyzed by acetic acid in controlled manners. Kinetic investigation reveals the copolymerization behavior of the two monomers. The random copolymers, named PAS, with high molecular weights between 22.0 and 43.6 kg/mol and tunable Ala molar fractions varying from 6% to 43% are able to be degraded by porcine pancreatic elastase within 50 days in mild conditions (pH=8.0 at 37 °C). Both the biodegradation rate and water solubility of PAS depend on the content of Ala residues. PAS with Ala fractions below 43% are soluble in water while the one with 43% Ala self-assembles in water into nanoparticles. Moreover, PAS are non-cytotoxic at the concentration of 5 mg/mL. The biodegradability and biocompatibility endow the Ala-containing PSar with potential to replace PEG as protective shield in drug-delivery.

Kinetics of the Imidazolium Ring-Opening of mRNA 5'-cap Analogs in Aqueous Alkali

2006 ◽  
Vol 71 (4) ◽  
pp. 567-578 ◽  
Author(s):  
Alicja Stachelska ◽  
Zbigniew J. Wieczorek ◽  
Janusz Stępiński ◽  
Marzena Jankowska-Anyszka ◽  
Harri Lönnberg ◽  
...  
Keyword(s):  
Electrostatic Interaction ◽  
Ring Opening ◽  
Nucleophilic Attack ◽  
Amino Groups ◽  
Hydroxide Ion ◽  
Methyl Group ◽  
Structural Modifications ◽  
Alkyl Groups ◽  
Imidazolium Ring ◽  
Kinetics Of

Second-order rate constants for the hydroxide-ion-catalyzed imidazolium ring-opening of several mono- and dinucleosidic analogs of mRNA 5'-cap have been determined. Intramolecular stacking of the two nucleobases in the dinucleosidic analogs, m7GpppN (m7G = 7-methylguanosine, N = 5'-linked nucleoside), and electrostatic interaction between the N-alkylated imidazolium ring and phosphate moiety have been shown to shield the m7G moiety against the nucleophilic attack of hydroxide ion. In addition, the effect of methylation of the nucleobase amino groups and replacement of the 7-methyl group with other alkyl groups have been studied. The influence of all the structural modifications studied turned out to be modest, the cleavage rates of the most and least reactive analogs (with the exception of non-phosphorylated nucleosides) differing only by a factor of 5.

scholarly journals Semi-Crystalline Hydrophobic Polyamidoamines: A New Family of Technological Materials?

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1018
Author(s):  
Massimo Marcioni ◽  
Jenny Alongi ◽  
Elisabetta Ranucci ◽  
Mario Malinconico ◽  
Paola Laurienzo ◽  
...  
Keyword(s):  
Maximum Stress ◽  
Water Resistance ◽  
Prolonged Exposure ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Molecular Weights ◽  
New Family ◽  
Methylene Groups ◽  
Methane Flame

The hitherto known polyamidoamines (PAAs) are not suitable as structural materials because they are usually water-soluble or swellable in water. This paper deals with the synthesis and characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-sec-amines with bis-acrylamides obtained from C6–C12 bis-prim-amines. H-PAAs were initially obtained in a solution of benzyl alcohol, a solvent suitable for both monomers and polymers. Their number average molecular weights, M¯n, which were determined with 1H-NMR by evaluating the percentage of their terminal units, varied from 6000 to >10,000. The solubility, thermal properties, ignitability and water resistance of H-PAAs were determined. They were soluble in organic solvents, semi-crystalline and thermally stable. The most promising ones were also prepared using a bulk process, which has never been previously reported for PAA synthesis. In the form of films, these H-PAAs were apparently unaffected by water. The films underwent tensile and wettability tests. They showed similar Young moduli (260–263 MPa), whereas the maximum stress and the stress at break depended on the number of methylene groups of the starting bis-acrylamides. Their wettability was somewhat higher than that of common Nylons. Interestingly, none of the H-PAAs considered, either as films or powders, ignited after prolonged exposure to a methane flame.

scholarly journals Desensitization Contributes to the Synaptic Response of Gain-of-Function Mutants of the Muscle Nicotinic Receptor

2006 ◽  
Vol 128 (5) ◽  
pp. 615-627 ◽  
Author(s):  
Sergio Elenes ◽  
Ying Ni ◽  
Gisela D. Cymes ◽  
Claudio Grosman
Keyword(s):  
Nicotinic Receptor ◽  
Dissociation Rate ◽  
Gain Of Function ◽  
Naturally Occurring ◽  
Channel Opening ◽  
Speed Up ◽  
High Concentrations ◽  
Dissociation Rate Constants ◽  
Kinetics Of ◽  
Peak Value

Although the muscle nicotinic receptor (AChR) desensitizes almost completely in the steady presence of high concentrations of acetylcholine (ACh), it is well established that AChRs do not accumulate in desensitized states under normal physiological conditions of neurotransmitter release and clearance. Quantitative considerations in the framework of plausible kinetic schemes, however, lead us to predict that mutations that speed up channel opening, slow down channel closure, and/or slow down the dissociation of neurotransmitter (i.e., gain-of-function mutations) increase the extent to which AChRs desensitize upon ACh removal. In this paper, we confirm this prediction by applying high-frequency trains of brief (∼1 ms) ACh pulses to outside-out membrane patches expressing either lab-engineered or naturally occurring (disease-causing) gain-of-function mutants. Entry into desensitization was evident in our experiments as a frequency-dependent depression in the peak value of succesive macroscopic current responses, in a manner that is remarkably consistent with the theoretical expectation. We conclude that the comparatively small depression of the macroscopic currents observed upon repetitive stimulation of the wild-type AChR is due, not to desensitization being exceedingly slow but, rather, to the particular balance between gating, entry into desensitization, and ACh dissociation rate constants. Disruption of this fine balance by, for example, mutations can lead to enhanced desensitization even if the kinetics of entry into, and recovery from, desensitization themselves are not affected. It follows that accounting for the (usually overlooked) desensitization phenomenon is essential for the correct interpretation of mutagenesis-driven structure–function relationships and for the understanding of pathological synaptic transmission at the vertebrate neuromuscular junction.

scholarly journals Influences of Molecular Weights on Physicochemical and Biological Properties of Collagen-Alginate Scaffolds

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 85 ◽  
Author(s):  
Truc Cong Ho ◽  
Jin-Seok Park ◽  
Sung-Yeoul Kim ◽  
Hoyeol Lee ◽  
Ju-Sop Lim ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Subcritical Water ◽  
Biological Properties ◽  
Ethanol Solution ◽  
Water Soluble ◽  
Potential Candidate ◽  
High Porosity ◽  
Engineering Applications ◽  
Molecular Weights

For tissue engineering applications, biodegradable scaffolds containing high molecular weights (MW) of collagen and sodium alginate have been developed and characterized. However, the properties of low MW collagen-based scaffolds have not been studied in previous research. This work examined the distinctive properties of low MW collagen-based scaffolds with alginate unmodified and modified by subcritical water. Besides, we developed a facile method to cross-link water-soluble scaffolds using glutaraldehyde in an aqueous ethanol solution. The prepared cross-linked scaffolds showed good structural properties with high porosity (~93%) and high cross-linking degree (50–60%). Compared with collagen (6000 Da)-based scaffolds, collagen (25,000 Da)-based scaffolds exhibited higher stability against collagenase degradation and lower weight loss in phosphate buffer pH 7.4. Collagen (25,000 Da)-based scaffolds with modified alginate tended to improve antioxidant capacity compared with scaffolds containing unmodified alginate. Interestingly, in vitro coagulant activity assay demonstrated that collagen (25,000 Da)-based scaffolds with modified alginate (C25-A63 and C25-A21) significantly reduced the clotting time of human plasma compared with scaffolds consisting of unmodified alginate. Although some further investigations need to be done, collagen (25,000 Da)-based scaffolds with modified alginate should be considered as a potential candidate for tissue engineering applications.

FRACTIONATION OF LIVETIN AND THE MOLECULAR WEIGHTS OF THE α- AND β-COMPONENTS

1957 ◽  
Vol 35 (4) ◽  
pp. 241-250 ◽  
Author(s):  
W. G. Martin ◽  
J. E. Vandegaer ◽  
W. H. Cook
Keyword(s):  
Light Scattering ◽  
Soluble Protein ◽  
Soluble Fraction ◽  
Egg Yolk ◽  
Water Soluble ◽  
Water Soluble Fraction ◽  
Molecular Weights ◽  
Water Soluble Protein ◽  
Hen Egg Yolk ◽  
Hen Egg

Livetin, the major water-soluble protein of hen egg yolk, was found to contain three major components having mobilities of −6.3, −3.8, and −2.1 cm.2 sec.−1 volt−1 at pH 8, µ 0.1, and these have been designated α-, β-, and γ-livetin respectively. The α- and β-livetins were separated and purified electrophoretically after removal of γ-livetin by precipitation from 37% saturated ammonium sulphate or 20% isopropanol. The α-, β-, and mixed livetins resembled pseudoglobulins in solubility but γ-livetin was unstable and this loss of solubility has, so far, prevented its characterization. Molecular weights determined by light scattering, osmotic pressure, and Archibald sedimentation procedure yielded respectively: 8.7, 7.8, and 6.7 × 104 for α-livetin, and 4.8, 5.0, and4.5 × 104 for β-livetin. Under suitable conditions of sedimentation and electrophoresis, egg yolk has been shown to contain three components having the same behavior as the three livetins of the water-soluble fraction.

scholarly journals Dissociation Rate Constants of Human Fibronectin Binding to Fibronectin-binding Proteins on LivingStaphylococcus aureusIsolated from Clinical Patients

2012 ◽  
Vol 287 (9) ◽  
pp. 6693-6701 ◽  
Author(s):  
Nadia N. Casillas-Ituarte ◽  
Brian H. Lower ◽  
Supaporn Lamlertthon ◽  
Vance G. Fowler ◽  
Steven K. Lower
Keyword(s):  
Rate Constants ◽  
Binding Proteins ◽  
Dissociation Rate ◽  
Human Fibronectin ◽  
Fibronectin Binding ◽  
Dissociation Rate Constants
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