Hydrolysis of 5-methylfuran-2-yl to 2,5-dioxopentanyl allows for stable bio-orthogonal proximity-induced ligation

AbstractLigation methodologies featuring bio-orthogonal units and leading to the formation of a stable adduct are the ideal candidates for being applied in a biological context. However, most of the available strategies rely on highly reactive species that require careful handling, or on the activation of pro-reactive functional groups. We here report on a proximity-induced ligation reaction that relies on a stable 2,5-dione, that can be conveniently generated under acidic conditions from a 2,5-dialkylfuran building block, and hydrazine nucleophiles. This bio-orthogonal ligation, which proceeds under physiological conditions, does not require any stimulus or trigger and leads to the formation of a pyridazinium adduct that demonstrates excellent stability under harsh conditions (24 h at 90 °C). The reaction was applied to the formation of PNA-PNA adducts, DNA- and RNA-templated ligations, and for the formation of peptide-peptide adducts in solution. This convenient methodology was further implemented on plastic and glass surfaces to realize self-addressable covalent constructs.

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Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20032019 ◽

2003 ◽

Vol 68 (10) ◽

pp. 2019-2031 ◽

Cited By ~ 1

Author(s):

Markéta Zukalová ◽

Jiří Rathouský ◽

Arnošt Zukal

Keyword(s):

Mesoporous Silica ◽

Ethylene Oxide ◽

Sodium Metasilicate ◽

Spherical Particles ◽

Structure Directing Agent ◽

Inorganic Species ◽

Poly Ethylene Oxide ◽

Acidic Conditions ◽

Poly Ethylene ◽

Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

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The Hsp60 Protein of Helicobacter Pylori Exhibits Chaperone and ATPase Activities at Elevated Temperatures

BioChem ◽

10.3390/biochem1010002 ◽

2021 ◽

Vol 1 (1) ◽

pp. 19-25

Author(s):

Jose A. Mendoza ◽

Julian L. Ignacio ◽

Christopher M. Buckley

Keyword(s):

Helicobacter Pylori ◽

Heat Stress ◽

Molecular Chaperone ◽

Elevated Temperatures ◽

Citrate Synthase ◽

Gastric Epithelium ◽

Acidic Conditions ◽

H Pylori ◽

Induced Aggregation ◽

Hydrolysis Of

The heat-shock protein, Hsp60, is one of the most abundant proteins in Helicobacter pylori. Given its sequence homology to the Escherichia coli Hsp60 or GroEL, Hsp60 from H. pylori would be expected to function as a molecular chaperone in this organism. H. pylori is a type of bacteria that grows on the gastric epithelium, where the pH can fluctuate between neutral and 4.5, and the intracellular pH can be as low as 5.0. We previously showed that Hsp60 functions as a chaperone under acidic conditions. However, no reports have been made on the ability of Hsp60 to function as a molecular chaperone under other stressful conditions, such as heat stress or elevated temperatures. We report here that Hsp60 could suppress the heat-induced aggregation of the enzymes rhodanese, malate dehydrogenase, citrate synthase, and lactate dehydrogenase. Moreover, Hsp60 was found to have a potassium and magnesium-dependent ATPase activity that was stimulated at elevated temperatures. Although, Hsp60 was found to bind GTP, the hydrolysis of this nucleotide could not be observed. Our results show that Hsp60 from H. pylori can function as a molecular chaperone under conditions of heat stress.

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Modified Rhamnogalacturonan-Rich Apple Pectin-Derived Structures: The Relation between Their Structural Characteristics and Emulsifying and Emulsion-Stabilizing Properties

Foods ◽

10.3390/foods10071586 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1586

Author(s):

Jessika N. Humerez-Flores ◽

Sarah H. E. Verkempinck ◽

Clare Kyomugasho ◽

Paula Moldenaers ◽

Ann M. Van Loey ◽

...

Keyword(s):

Emulsion Stability ◽

Structural Characteristics ◽

Stability Study ◽

Natural Food ◽

Apple Pectin ◽

Oil Droplets ◽

Food Ingredients ◽

Acidic Conditions ◽

Hydrolysis Of ◽

Subsequent Acid

In the context of the increasing interest in natural food ingredients, the emulsifying and emulsion-stabilizing properties of three rhamnogalacturonan-rich apple pectin-derived samples were assessed by evaluating a range of physicochemical properties. An apple pectin (AP74) was structurally modified by a β-eliminative reaction to obtain a RG-I-rich pectin sample (AP-RG). Subsequent acid hydrolysis of AP-RG led to the generation of pectin material with partially removed side chains (in particular arabinose depleted) (AP-RG-hydrolyzed), thus exhibiting differences in rhamnose, arabinose, and galactose in comparison to AP-RG. All samples exhibited surface activity to some extent, especially under acidic conditions (pH 2.5). Furthermore, the viscosity of the samples was assessed in relation to their emulsion-stabilizing properties. In a stability study, it was observed that the non-degraded AP74 sample at pH 2.5 exhibited the best performance among all the apple pectin-derived samples evaluated. This emulsion presented relatively small oil droplets upon emulsion production and was less prone to creaming than the emulsions stabilized by the (lower molecular weight) RG-I-rich materials. The AP-RG and AP-RG-hydrolyzed samples presented a slightly better emulsion stability at pH 6.0 than at pH 2.5. Yet, neither pectin sample was considered having good emulsifying and emulsion-stabilizing properties, indicated by the presence of coalesced and flocculated oil droplets.

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Theoretical study on the reaction mechanism for the hydrolysis of esters and amides under acidic conditions

Tetrahedron ◽

10.1016/j.tet.2006.11.039 ◽

2007 ◽

Vol 63 (5) ◽

pp. 1264-1269 ◽

Cited By ~ 31

Author(s):

Kenzi Hori ◽

Yutaka Ikenaga ◽

Kouichi Arata ◽

Takanori Takahashi ◽

Kenji Kasai ◽

...

Keyword(s):

Reaction Mechanism ◽

Theoretical Study ◽

Acidic Conditions ◽

Hydrolysis Of Esters ◽

Hydrolysis Of

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Effect of Cytokinins on the Expansion and Metabolism of Excised Cucumber Cotyledons

Functional Plant Biology ◽

10.1071/pp9800227 ◽

1980 ◽

Vol 7 (3) ◽

pp. 227

Author(s):

C Tsui ◽

Tao Guo-qing ◽

Chen Hui-ying ◽

Son Yan-ru ◽

Lian Han-ping ◽

...

Keyword(s):

Nucleic Acid ◽

Soluble Sugars ◽

Dry Weight ◽

Acid Synthesis ◽

Cell Number ◽

Cucumis Sativus L ◽

Biochemical Processes ◽

Dna And Rna ◽

Lag Period ◽

Hydrolysis Of

Expansion of excised cucumber (Cucumis sativus L.) cotyledons was stimulated by treatment with cytokinin, and commenced after a lag period of about 4 h. Expansion induced by benzyladenine (BA) was due mainly to increase of fresh weight, but cell number increased slightly. Hydrolysis of protein and lipid was stimulated by BA, and soluble sugars increased simultaneously. However, there was no significant change in the dry weight of cotyledons during the period of expansion. It is assumed that the transformation of lipid to sugar in the cotyledon is stimulated by BA. The respiration of cotyledons was evidently stimulated by BA and was entirely inhibited by respiratory inhibitors, e.g. NaN,, malonate and dinitrophenol. Inhibitors of protein and nucleic acid synthesis, such as chloramphenicol and actinomycin D, inhibited only the BA-induced expansion. They had no effect on the expansion of controls. These results suggest that different biochemical processes are involved in the expansion of cotyledons induced by BA and in controls. The former is related not only to respiration but also to the synthesis of protein and nucleic acid. BA increased DNA and RNA content per cotyledon. The increase of total RNA is due mainly to the increase of 25 S and 18 S rRNA.

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Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

Butlerov Communications ◽

10.37952/roi-jbc-01/20-63-7-126 ◽

2020 ◽

Vol 63 (7) ◽

pp. 126-132

Author(s):

Lyubov V. Furda ◽

◽

Evgenia A. Tarasenko ◽

Sofya N. Dudina ◽

Olga E. Lebedeva ◽

...

Keyword(s):

Surface Area ◽

Sol Gel ◽

Molar Ratio ◽

Active Centers ◽

Indicator Method ◽

Synthesis Conditions ◽

Alkaline Conditions ◽

Acidic Conditions ◽

Amphoteric Properties ◽

Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

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Flavylium Dye as pH-Tunable Fluorescent and CD Probe for Double-Stranded DNA and RNA

Chemosensors ◽

10.3390/chemosensors8040129 ◽

2020 ◽

Vol 8 (4) ◽

pp. 129

Author(s):

Ivo Crnolatac ◽

Letícia Giestas ◽

Gordan Horvat ◽

António Jorge Parola ◽

Ivo Piantanida

Keyword(s):

Steady State ◽

Detection Limit ◽

Rna Secondary Structure ◽

Binding Affinities ◽

Cationic Form ◽

Rna Detection ◽

Time Resolved ◽

Dna And Rna ◽

Double Stranded Dna ◽

Acidic Conditions

The interaction of 4′-(N,N-dimethylamino)-6-hydroxyflavylium cation with double stranded (ds-) DNA/RNA was studied by UV/Vis spectrophotometry, circular dichroism (CD), and also steady-state and time-resolved emission spectroscopies at neutral and weakly acidic conditions. At pH 5, the studied molecule, in its flavylium cationic form, showed considerable binding affinities (5 < logKs < 6) for all ds-DNA/RNA, contrary to chalcones forms (dominant at pH 7), which did not show binding to polynucleotides. Flavylium cation intercalated into ds-DNAs at variance to dominant groove aggregation within ds-RNA, which was reported by RNA-specific bisignate induced CD spectrum (ICD) bands. The intrinsically negligible fluorescence of flavylium was strongly increased upon the addition of DNA or RNA, whereby both the fluorescence intensity and emission lifetimes of complexes differed considerably: the strongest emission increase was observed for AU-RNA (detection limit estimated to 10 nM) followed by AT-DNAs and the much weaker effect of GC-DNAs. Both fluorescence sensitivity on the ds-DNA/RNA secondary structure and sequence-selective ICD bands make the flavylium–chalcones system an intriguing pH-switchable new probe for distinguishing between various polynucleotide sequences.

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Hydrolysis of borate-glass surfaces

Glass and Ceramics ◽

10.1007/bf00677862 ◽

1992 ◽

Vol 49 (8) ◽

pp. 365-367

Author(s):

E. V. Spiridonova

Keyword(s):

Borate Glass ◽

Glass Surfaces ◽

Hydrolysis Of

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Towards a Non-Biased Formaldehyde Quantification in Leather: New Derivatization Conditions before HPLC Analysis of 2,4-Dinitrophenylhydrazine Derivatives

Molecules ◽

10.3390/molecules25235765 ◽

2020 ◽

Vol 25 (23) ◽

pp. 5765

Author(s):

Caroline Bourgeois ◽

Nicolas Blanc ◽

Jean-Claude Cannot ◽

Claire Demesmay

Keyword(s):

Hplc Analysis ◽

Orthophosphoric Acid ◽

Reversed Phase ◽

Precolumn Derivatization ◽

Reversed Phase Liquid Chromatography ◽

Formaldehyde Content ◽

Buffer Solutions ◽

Phase Liquid ◽

Acidic Conditions ◽

Hydrolysis Of

In leathers, formaldehyde is currently analyzed according to EN ISO 17226-1 standard, by reversed phase liquid chromatography after off-line precolumn derivatization with 2,4 dinitrophenylhydrazine (DNPH) in strong acidic conditions. We first demonstrate that this standard is not adapted to leather retanned with resins likely to release formaldehyde by hydrolysis. Indeed, formaldehyde content may be largely overestimated due to concomitant resin hydrolysis (in harsh acidic conditions) that releases formaldehyde during the derivatization step and during the waiting time on autosampler before analysis. Therefore, we thoroughly studied the derivatization step in order to propose new derivatization conditions. Replacing orthophosphoric acid by less acidic buffer solutions is not enough to avoid hydrolysis. A derivatization without adding acid is realized by solubilizing DNPH in acetonitrile instead of orthophosphoric acid. These conditions lead to a complete derivatization of formaldehyde in 3 h at 50 °C (in a water bath) while avoiding the hydrolysis of co-extracted dicyandiamide and melamine resins. The as-obtained leather extracts are stable over time. Formaldehyde contents found with this method agree with the formaldehyde content measured immediately at the end of derivatization reaction in standard conditions or with formaldehyde content measured by a home-designed flow injection analysis with acetylacetone online derivatization and UV detection.

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Potential GABAB Receptor Antagonists. III. Folded Baclofen Analogs Based on Phthalide

Australian Journal of Chemistry ◽

10.1071/ch9890787 ◽

1989 ◽

Vol 42 (6) ◽

pp. 787 ◽

Cited By ~ 13

Author(s):

C Donati ◽

RH Prager ◽

B Weber

Keyword(s):

Ethyl Acetoacetate ◽

Gabab Receptor ◽

Hydrazoic Acid ◽

Receptor Antagonists ◽

Keto Ester ◽

Acidic Conditions ◽

Gabab Receptor Antagonists ◽

Hydrolysis Of ◽

Parallel Series

Possible analogues of baclofen, 3-aminomethyl-5-chloro-, 3-aminomethyl-6-chloro- and 3-aminomethyl-5,6-dichloro-isobenzofuran-1(3H)-one, have been prepared for evaluation as antispasticity agents. The corresponding 3-hydroxyisobenzofuran-l(3H)-one was reacted with ethyl acetoacetate under acidic conditions, and the keto ester hydrolysed and decarboxylated to give the 3-(2-oxopropyl)isobenzofuran-l(3H)-one; this was treated with hydrazoic acid, and the product was hydrolysed. A parallel series of (3-oxo-1,3-dihydroisobenzofuran-1-y1)glycines was obtained by treating the keto ester first with hydrazoic acid, and hydrolysis of the resulting acetamides.

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