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31.
Natural biopolymers from plant sources contain many impurities (e.g., fat, protein, fiber, natural pigment and endogenous enzymes), therefore, an efficient purification process is recommended to minimize these impurities and consequently improve the functional properties of the biopolymer. The main objective of the present study was to investigate the effect of different purification techniques on the yield, protein content, solubility, water- and oil-holding capacity of a heteropolysaccharide-protein biopolymer obtained from durian seed. Four different purification methods using different chemicals and solvents (i.e., A (isopropanol and ethanol), B (isopropanol and acetone), C (saturated barium hydroxide), and D (Fehling solution)] to liberate the purified biopolymer from its crude form were compared. In most cases, the purification process significantly (p < 0.05) improved the physicochemical properties of heteropolysaccharide-protein biopolymer from durian fruit seed. The present work showed that the precipitation using isopropanol and acetone (Method B) resulted in the highest purification yield among all the tested purification techniques. The precipitation using saturated barium hydroxide (Method C) led to induce the highest solubility and relatively high capacity of water absorption. The current study reveals that the precipitation using Fehling solution (Method D) most efficiently eliminates the protein fraction, thus providing more pure biopolymer suitable for biological applications. 相似文献
32.
Gholam Hossein Rounaghi Bahareh Nouri Somayeh Tarahomi 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(3-4):331-338
The complexation reaction of N-phenylaza-15-crown-5 (PhA15C5) with UO2 2+ cation was studied in acetonitrile–methanol (AN–MeOH), acetonitrile–butanol (AN–BuOH), acetonitrile–dimethylformamide (AN–DMF) and methanol–propylencarbonate (MeOH–PC) binary solutions, at different temperatures by conductometry method. The conductance data show that the stoichiometry of the complex formed between PhA15C5 with UO2 2+ cation in most cases is 1:1 [M:L], but in some solvent systems a 1:2 [M:L2] complex is formed in solutions. The results revealed that, the stability constant of (PhA15C5·UO2)2+ complex in the binary mixed solvents varies in the order: AN–BuOH>AN–MeOH>AN–DMF. In the case of the pure organic solvents, the sequence of the stability of the complex changes as: AN>PC>BuOH>DMF. A non-linear relationship was observed for changes of logKf of (PhA15C5·UO2)2+ complex versus the composition of the binary mixed solvents. The corresponding standard thermodynamic parameters (ΔHc°, ΔSc°) were obtained from temperature dependence of the stability constant. The results show that the values and also the sign of these parameters are influenced by the nature and composition of the mixed solvents. 相似文献
33.
Ahmed N Suresh V Shirinfar B Geronimo I Bist A Hwang IC Kim KS 《Organic & biomolecular chemistry》2012,10(10):2094-2100
Cyclo-bis-(urea-3,6-dichlorocarbazole) (1) forms a 1 : 2 complex with CH(3)CO(2)(-) and H(2)PO(4)(-) through hydrogen bonding with the two urea moieties, resulting in fluorescence enhancement via a combined photoinduced electron transfer (PET) and energy transfer mechanism. The binding mechanism involves a conformational change of the two urea receptors to a trans orientation after binding of the first anion, which facilitates the second interaction. 相似文献
34.
An insight to the molecular interactions of the FDA approved HIV PR drugs against L38L↑N↑L PR mutant
Zainab K. Sanusi Thavendran Govender Glenn E. M. Maguire Sibusiso B. Maseko Johnson Lin Hendrik G. Kruger Bahareh Honarparvar 《Journal of computer-aided molecular design》2018,32(3):459-471
The aspartate protease of the human immune deficiency type-1 virus (HIV-1) has become a crucial antiviral target in which many useful antiretroviral inhibitors have been developed. However, it seems the emergence of new HIV-1 PR mutations enhances drug resistance, hence, the available FDA approved drugs show less activity towards the protease. A mutation and insertion designated L38L↑N↑L PR was recently reported from subtype of C-SA HIV-1. An integrated two-layered ONIOM (QM:MM) method was employed in this study to examine the binding affinities of the nine HIV PR inhibitors against this mutant. The computed binding free energies as well as experimental data revealed a reduced inhibitory activity towards the L38L↑N↑L PR in comparison with subtype C-SA HIV-1 PR. This observation suggests that the insertion and mutations significantly affect the binding affinities or characteristics of the HIV PIs and/or parent PR. The same trend for the computational binding free energies was observed for eight of the nine inhibitors with respect to the experimental binding free energies. The outcome of this study shows that ONIOM method can be used as a reliable computational approach to rationalize lead compounds against specific targets. The nature of the intermolecular interactions in terms of the host–guest hydrogen bond interactions is discussed using the atoms in molecules (AIM) analysis. Natural bond orbital analysis was also used to determine the extent of charge transfer between the QM region of the L38L↑N↑L PR enzyme and FDA approved drugs. AIM analysis showed that the interaction between the QM region of the L38L↑N↑L PR and FDA approved drugs are electrostatic dominant, the bond stability computed from the NBO analysis supports the results from the AIM application. Future studies will focus on the improvement of the computational model by considering explicit water molecules in the active pocket. We believe that this approach has the potential to provide information that will aid in the design of much improved HIV-1 PR antiviral drugs. 相似文献
35.
A facile method for the synthesis of various propargylamines derivatives with different structural parts has been reported. The reaction has consisted of one-pot coupling between aldehydes, secondary amines and terminal alkynes using CuCl as a catalyst and choline chloride/urea DES as a cheap and biocompatible reaction media. The procedure is free of using toxic solvents and used CuCl as an available, inexpensive and non-toxic catalyst. Using this methodology, 15 different propargylamine derivatives were successfully synthesized at 60 °C in 15 hr, mostly in good yields. 相似文献
36.
Farhood Bagher Geraily Ghazale Abtahi Seyed Mohammad Mahdi Ghorbani Mahdi Mehdikhani Mohamad 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):1041-1050
Journal of Radioanalytical and Nuclear Chemistry - In the current study, dose rate and photon energy dependence of PASSAG gel dosimeter is evaluated by using MRI technique. The gel samples were... 相似文献
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38.
Azimi Bahareh Maleki Homa Gigante Vito Bagherzadeh Roohollah Mezzetta Andrea Milazzo Mario Guazzelli Lorenzo Cinelli Patrizia Lazzeri Andrea Danti Serena 《Cellulose (London, England)》2022,29(6):3079-3129
Cellulose - Cellulose, a natural, renewable, and environment friendly biopolymer, has been considered as a sustainable feedstock in the near future. However, only 0.3% of cellulose is today... 相似文献
39.
We have recently shown that, for 2 < p < ∞, a locally compact group G is compact if and only if the convolution multiplication f * g exists for all f, g ∈ L p (G). Here, we study the existence of f * g for all f, g ∈ L p (G) in the case where 0 < p ≤ 2. Also, for 0 < p < ∞, we offer some necessary and sufficient conditions for L p (G) * L p (G) to be contained in certain function spaces on G. 相似文献
40.
The article shows a simple way of calibrating the strength of the theory of positive induction, ID*1{{\rm ID}^{*}_{1}} . Crucially the proof exploits the equivalence of S11{\Sigma^{1}_{1}} dependent choice and ω-model reflection for P12{\Pi^{1}_{2}} formulae over ACA
0. Unbeknown to the authors, D. Probst had already determined the proof-theoretic strength of ID*1{{\rm ID}^{*}_{1}} in Probst, J Symb Log, 71, 721–746, 2006. 相似文献