Formation of borate complexes of inosamines (aminodeoxyinositols) and their separation by paper electrophoresis

1974 ◽  
Vol 27 (4) ◽  
pp. 853 ◽  
Author(s):  
JL Frahn ◽  
JA Mills
Keyword(s):  
Carbon Dioxide ◽  
Paper Electrophoresis ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Amino Group ◽  
Ph Values ◽  
Borate Complex ◽  
Wide Range ◽  
Borate Complexes ◽  
Probable Site

The electrophoretic mobility of an inosamine in borate buffer is very dependent on configuration, and a set of 10 inosamines showed a wide range of mobilities. The order of mobilities within the set changed as the pH of the buffer was changed in the range 7.7-9.5. Paper electrophoresis in borate buffers can effectively separate mixtures of inosamines. The probable site of reaction between an inosamine and borate ions has been identified for some isomers. In aminodeoxy-scyllo-inositol and 3-amino-3-deoxy-epi-inositol the amino group is involved in the formation of a tridentate borate complex of adamantane-type structure, which is electrically neutral over the above range of pH values. Aminodeoxy-scyllo-inositol simultaneously combines with a second molecule of borate, forming a bis-tridentate complex with one anionic centre. There is evidence that in other isomers protonation of the amino group and formation of anionic borate complexes at hydroxyl groups are not independent reactions. Paper electrophoresis in non-complexing buffers provides evidence for the relative basicities of inosamines. DL-2-Amino-2-deoxy-epi-inositol, which has an interaction between axial amino and hydroxyl group in the preferred conformation, was the strongest base in the set, whereas the bases with an axial amino group free of such an interaction were the weakest. Inosamines form N-carboxyl derivatives in the normal way on exposure to carbon dioxide in the presence of strong alkali.

scholarly journals Study of the Reactivity of Lignin Model Compounds to Fluorobenzylation Using 13C and 19F NMR: Application to Lignin Phenolic Hydroxyl Group Quantification by 19F NMR

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3211
Author(s):  
Esakkiammal Sudha Esakkimuthu ◽  
Nathalie Marlin ◽  
Marie-Christine Brochier-Salon ◽  
Gérard Mortha
Keyword(s):  
Reaction Medium ◽  
19F Nmr ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Nmr Analysis ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Wide Range ◽  
Lignin Model ◽  
13C And 19F Nmr

Lignin is an aromatic biopolymer derived from lignocellulosic biomass. Providing a comprehensive structural analysis of lignin is the primary motivation for the quantification of various functional groups, with a view to valorizing lignin in a wide range of applications. This study investigated the lignin fluorobenzylation reaction and performed a subsequent 19F-NMR analysis to quantify hydroxyl groups, based on a work developed two decades ago by Barrelle et al. The objectives were to check the assignments proposed in this previous study and to examine the reactivity of various types of lignin hydroxyls with the derivatization agent. Selected lignin model compounds containing phenolic and aliphatic hydroxyls were subjected to the fluorobenzylation reaction, and the obtained reaction medium was analyzed by 13C and 19F NMR spectroscopy. The model compound results showed that phenolic hydroxyls were totally derivatized, whereas aliphatic hydroxyls underwent minimal conversion. They also confirmed that 19F NMR chemical shifts from −115 ppm to −117.3 ppm corresponded to phenolic groups. Then, a 19F NMR analysis was successfully applied to Organosolv commercial lignin after fluorobenzylation in order to quantify its phenolic group content; the values were found to be in the range of the reported values using other analytical techniques after lignin acetylation.

scholarly journals Novel α- and β-Amino Acid Inhibitors of Influenza Virus Neuraminidase

2001 ◽  
Vol 45 (9) ◽  
pp. 2563-2570 ◽  
Author(s):  
Warren M. Kati ◽  
Debra Montgomery ◽  
Clarence Maring ◽  
Vincent S. Stoll ◽  
Vincent Giranda ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Neuraminidase Inhibitor ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Side Chains ◽  
Amino Group ◽  
Amino Groups ◽  
Acetylneuraminic Acid ◽  
Cell Culture Assay ◽  
Influenza Virus Neuraminidase

ABSTRACT In an effort to discover novel, noncarbohydrate inhibitors of influenza virus neuraminidase we hypothesized that compounds which contain positively charged amino groups in an appropriate position to interact with the Asp 152 or Tyr 406 side chains might be bound tightly by the enzyme. Testing of 300 α- and β-amino acids led to the discovery of two novel neuraminidase inhibitors, a phenylglycine and a pyrrolidine, which exhibited K i values in the 50 μM range versus influenza virus A/N2/Tokyo/3/67 neuraminidase but which exhibited weaker activity against influenza virus B/Memphis/3/89 neuraminidase. Limited optimization of the pyrrolidine series resulted in a compound which was about 24-fold more potent than 2-deoxy-2,3-dehydro-N-acetylneuraminic acid in an anti-influenza cell culture assay using A/N2/Victoria/3/75 virus. X-ray structural studies of A/N9 neuraminidase-inhibitor complexes revealed that both classes of inhibitors induced the Glu 278 side chain to undergo a small conformational change, but these compounds did not show time-dependent inhibition. Crystallography also established that the α-amino group of the phenylglycine formed hydrogen bonds to the Asp 152 carboxylate as expected. Likewise, the β-amino group of the pyrrolidine forms an interaction with the Tyr 406 hydroxyl group and represents the first compound known to make an interaction with this absolutely conserved residue. Phenylglycine and pyrrolidine analogs in which the α- or β-amino groups were replaced with hydroxyl groups were 365- and 2,600-fold weaker inhibitors, respectively. These results underscore the importance of the amino group interactions with the Asp 152 and Tyr 406 side chains and have implications for anti-influenza drug design.

Carbon-13 Resonance Spectroscopic Studies on the Formation of Borate and Diphenylborinate Complexes of Polyhydroxy Compounds

1973 ◽  
Vol 51 (19) ◽  
pp. 3277-3286 ◽  
Author(s):  
Philip A. J. Gorin ◽  
Mytosk Mazurek
Keyword(s):  
Molecular Weight ◽  
Magnetic Resonance ◽  
Spectroscopic Studies ◽  
Sodium Tetraborate ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Polyhydroxy Compounds ◽  
Borate Complex ◽  
Equilibrium Reactions ◽  
Borate Complexes

On complexing with sodium tetraborate the 13C magnetic resonance (c.m.r.) spectra of certain sugars contain considerably broadened signals. Replacement of the reagent with sodium diphenylborinate resulted in spectra with sharp singlets corresponding to the diphenylborinate complex, indicating that 13C-11B coupling likely does not occur. Most of the broadening is due rather to either the presence of more than one conformer of the borate complex or the rapid interconversion of the compound with borate complexes of types II and III. In one group of experiments the complexing of diphenylborinate with several low molecular weight sugars and polysaccharides was followed through c.m.r. spectroscopy. In another, complexing was observed with pyranosides having 1,3-hydroxyl groups with orientations that were almost diaxial. In the equilibrium reactions the approximate extent of complexing was estimated and with compounds that can form more than one complex, such as glycerol, the number and structures of the complexes were determined.

scholarly journals Theoretical Study of 2-(Trifluoromethyl)phenothiazine Derivatives with Two Hydroxyl Groups in the Side Chain-DFT and QTAIM Computations

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5242
Author(s):  
Andrzej Poła ◽  
Anna Palko-Łabuz ◽  
Kamila Środa-Pomianek
Keyword(s):  
Quantum Chemical ◽  
Biological Effects ◽  
Chemical Properties ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Hydroxyl Groups ◽  
Dissociation Enthalpy ◽  
Wide Range ◽  
Thermochemical Parameters ◽  
Intramolecular Hydrogen

Phenothiazines are known as synthetic antipsychotic drugs that exhibit a wide range of biological effects. Their properties result from the structure and variability of substituents in the heterocyclic system. It is known that different quantum chemical properties have a significant impact on drug behavior in the biological systems. Thus, due to the diversity in the chemical structure of phenothiazines as well as other drugs containing heterocyclic systems, quantum chemical calculations provide valuable methods in predicting their activity. In our study, DFT computations were applied to show some thermochemical parameters (bond dissociation enthalpy—BDE, ionization potential—IP, proton dissociation enthalpy—PDE, proton affinity—PA, and electrontransfer enthalpy—ETE) describing the process of releasing the hydrogen/proton from the hydroxyl group in the side chain of four 2-(trifluoromethyl)phenothiazine (TFMP) derivatives and fluphenazine (FLU). Additional theoretical analysis was carried out based on QTAIM theory. The results allowed theoretical determination of the ability of compounds to scavenge free radicals. In addition, the intramolecular hydrogen bond (H-bond) between the H-atom of the hydroxyl group and the N-atom located in the side chain of the investigated compounds has been identified and characterized.

Unusual chemical properties of the amino groups of insulin: implications for structure–function relationship

1979 ◽  
Vol 57 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Marla G. Sheffer ◽  
Harvey Kaplan
Keyword(s):  
Carbon Dioxide ◽  
Acetic Anhydride ◽  
Chemical Properties ◽  
Amino Terminus ◽  
Amino Group ◽  
Amino Groups ◽  
Ph Values ◽  
Function Relationship ◽  
Ph Range ◽  
Association State

The chemical properties of the three amino groups of insulin were obtained at 10 and 37 °C using the competitive labelling technique with acetic anhydride as the labelling reagent. At 10 °C, pK values of 7.9, 7.2, and 7.8 were found for the glycyl A1, phenylalanyl B1, and lysyl B29 amino groups. When compared with standard amino compounds by means of a Brønsted plot, the two amino-termini were found to be 'super-reactive' and the lysyl ε-amino group buried. In the presence of carbon dioxide at physiological pH values, all three amino groups became much less reactive indicating that they had reacted to form carbamino derivatives. Above pH 8 the reactivities of the glycyl amino terminus and ε-amino group increase sharply indicating that insulin is undergoing a conformational change which is most likely a change in its association state. At 37 °C the amino groups do not titrate normally but exhibit sharp increases in reactivity over the physiological pH range with the midpoints in the pH reactivity profiles between pH values of 7.0 and 7.3. This behaviour is interpreted as a rapid disaggregation of insulin to form monomers as a result of the ionization of the amino groups. It is concluded that at physiological pH and temperature all three amino groups are deprotonated.

scholarly journals Defluoridation performance comparison of aluminum hydroxides with different crystalline phases

2022 ◽  
Author(s):  
Wei-Zhuo Gai ◽  
Shi-Hu Zhang ◽  
Yang Yang ◽  
Kexi Sun ◽  
Hong Jia ◽  
...  
Keyword(s):  
Aluminum Hydroxide ◽  
Performance Comparison ◽  
Hydroxyl Group ◽  
Fluoride Removal ◽  
Hydroxyl Groups ◽  
Order Kinetic ◽  
Crystalline Phases ◽  
Surface Hydroxyl ◽  
Ph Values ◽  
Aluminum Hydroxides

Abstract Aluminum hydroxide is an eye catching and extensively researched adsorbent for fluoride removal and its defluoridation performance is closely related to the preparation method and crystalline phase. In this research, the defluoridation performances of aluminum hydroxides with different crystalline phases are compared and evaluated in terms of fluoride removal capacity, sensitivity to pH values and residual Al contents after defluoridation. It is found that the defluoridation performance of different aluminum hydroxides follows the order of boehmite > bayerite > gibbsite. The fluoride adsorption on aluminum hydroxides follows pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum defluoridation capacities of boehmite, bayerite and gibbsite are 42.08, 2.97 and 2.74 mg m−2, respectively. The pH values and FTIR analyses reveal that the ligand exchange between fluoride and surface hydroxyl groups is the fluoride removal mechanism. Different aluminum hydroxides have different surface hydroxyl group densities, which results in the different defluoridation capacities. This work provides a new idea to prepare aluminum hydroxide with outstanding defluoridation performance.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

scholarly journals Analysis of the possibility and molecular mechanism of carbon dioxide consumption in the Diels-Alder processes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Karolina Kula ◽  
Agnieszka Kącka-Zych ◽  
Agnieszka Łapczuk-Krygier ◽  
Radomir Jasiński
Keyword(s):  
Carbon Dioxide ◽  
Molecular Mechanism ◽  
Lewis Acids ◽  
Chemical Reactivity ◽  
Carbon Dioxide Concentration ◽  
Diels Alder ◽  
Wide Range ◽  
Bet Analysis ◽  
Earth’S Climate ◽  
Step Mechanism

Abstract The large and significant increase in carbon dioxide concentration in the Earth’s atmosphere is a serious problem for humanity. The amount of CO2 is increasing steadily which causes a harmful greenhouse effect that damages the Earth’s climate. Therefore, one of the current trends in modern chemistry and chemical technology are issues related to its utilization. This work includes the analysis of the possibility of chemical consumption of CO2 in Diels-Alder processes under non-catalytic and catalytic conditions after prior activation of the C=O bond. In addition to the obvious benefits associated with CO2 utilization, such processes open up the possibility of universal synthesis of a wide range of internal carboxylates. These studies have been performed in the framework of Molecular Electron Density Theory as a modern view of the chemical reactivity. It has been found, that explored DA reactions catalyzed by Lewis acids with the boron core, proceeds via unique stepwise mechanism with the zwitterionic intermediate. Bonding Evolution Theory (BET) analysis of the molecular mechanism associated with the DA reaction between cyclopentadiene and carbon dioxide indicates that it takes place thorough a two-stage one-step mechanism, which is initialized by formation of C–C single bond. In turn, the DA reaction between cyclopentadiene and carbon dioxide catalysed by BH3 extends in the environment of DCM, indicates that it takes place through a two-step mechanism. First path of catalysed DA reaction is characterized by 10 different phases, while the second by eight topologically different phases.

Sign in / Sign up

Export Citation Format

Share Document