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The catalytic mechanism of a -dependent family 92 -mannosidase, which is abundantly present in human gut flora and malfunctions leading to the lysosomal storage disease α-mannosidosis, has been investigated using quantum mechanics/molecular mechanics and metadynamics methods. Computational efforts show that the enzyme follows a conformational itinerary of and the ion serves a dual purpose, as it not only distorts the sugar ring but also plays a crucial role in orchestrating the arrangement of catalytic residues. This orchestration, in turn, contributes to the facilitation of conformers for the ensuing reaction. This mechanistic insight is well-aligned with the experimental predictions of the catalytic pathway, and the computed energies are of the same order of magnitude as the experimental estimations. Hence, our results extend the mechanistic understanding of glycosidases. 相似文献
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Kantekin Halit Dilber Gülsev Gök Yasar Ocak Ümmühan Abbasoğlu Rıza 《Transition Metal Chemistry》2003,28(1):51-57
The novel (E,E)-dioxime, 5,6:ll,12:17,18-tribenzo-2,3-bis(hydroxyimino)-7,16-dithia-9, 14-dioxo-l,4,10,13-tetraazacyclooctadecane (H2L) has been synthesized by reacting (E,E)-dichloroglyoxime (2) with 2,3:8,9:14,15-tribenzo-4,13-di-thia-6,11-dioxa-l,7,10,16-tetraazahexzadecane (3), prepared by the reaction of N,N-bis(chloroacetyl)-1, 2-phenylene-diamine (1) with 2-aminothiophenol. Mononuclear complexes (4, 5) of this ligand have been synthesized by reacting the vic-dioxime (H2L) with K2PtCl4 and NiCl2 · 6H2O, respectively. Heterotrinuclear complexes (6)and(7) have been prepared by the reaction of (4) and (5) mononuclear complexes with [Cu(MeCN)4]PF6. The structures of the vic-dioxime and its mono and trinuclear complexes were identified by elemental analysis, 1H- and 13C-n.m.r, i.r. and m.s. data. 相似文献
44.
Reduction of 2,3:9,10-dibenzo-5,12-diaza-1,8-dioxacylotetradecane-5,11-diene( 1 ) with sodium borohydride in ethanol generates 2,3:9,10-dibenzo-5,12-diaza-1,8-dioxacyclotetradecane( 2 ) in high yield. The macrocyclic ligand 2,3:9,10-dibenzo-5,12-diaza-1,8-dioxacyclotetradecane-N,N′-diacetic acid ( 3 ) has been synthesized and characterized. In addition, reaction of ( 2 ) with an excess of acrylonitrile gives 2,3:9,10-dibenzo-5,12-diaza-1,8-dioxacyclotetradecane-N,N′-di(2-cyanoethyl) ( 4 ). Several new complexes of these ligands with nickel(II), copper(II) and cobalt(II) have been prepared and identified. The structures of these complexes are proposed on the basis of elemental analysis, 1H, 13C-NMR, IR, UV-VIS spectra, magnetic susceptibility and conductivity data. 相似文献
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Faiza Naureen Yasar Shah Sayyed Ibrahim Shah Muhammad Abbas Inayat Ur Rehman Salar Muhammad Hamdullah Khang Wen Goh Fazli Khuda Amjad Khan Siok Yee Chan Mehwish Mushtaq Long Chiau Ming 《Molecules (Basel, Switzerland)》2022,27(13)
Mirtazapine is a tetracyclic anti-depressant with poor water solubility. The aim of this study was to improve the dissolution rate of mirtazapine by delivering the drug as a liquisolid compact. Central composite design (CCD) was employed for the preparation of mirtazapine liquisolid compacts. In this, the impacts of two independent factors, i.e., excipient ratio (carrier:coating) and different drug concentration on the response of liquisolid system were optimized. Liquisolid compacts were prepared using propylene glycol as a solvent, microcrystalline cellulose as a carrier, and silicon dioxide (Aerosil) as the coating material. The crystallinity of the formulated drug and the interactions between the excipients were examined using X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), respectively. The dissolution study for the liquisolid compact was carried out as per FDA guidelines. The results showed loss of crystallinity of the mirtazapine in the formulation and was completely solubilized in non-volatile solvent and equally dispersed throughout the powder system. Moreover, drug dissolution was found to be higher in liquisolid compacts than the direct compressed conventional tablets (of mirtazapine). The liquisolid technique appears to be a promising approach for improving the dissolution of poorly soluble drugs like mirtazapine. 相似文献
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Kavil Yasar N. Shaban Yasser A. Alelyani Saeed Saad Al-Farawati Radwan Orif Mohammad I. Ghandourah Mohammed A. Schmidt Mark Turki Adnan J. Zobidi Mousa 《Research on Chemical Intermediates》2020,46(1):755-768
Research on Chemical Intermediates - The effluents containing the discarded water from the textile industry are graded as one of the foremost pollutants in all industrial sectors. The wide... 相似文献
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Central European Journal of Operations Research - The objective of this study was to examine the change in efficiency of health care systems of 34 OECD countries between 2000 and 2012, a period... 相似文献
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In this paper we are concerned with the oscillation of solutions of a certain more general higher order nonlinear neutral
type functional differential equation with oscillating coefficients. We obtain two sufficient criteria for oscillatory behaviour
of its solutions. 相似文献
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Mehmet Özer Yasar Polatoglu Gürsel Hacibekiroglou Antonios Valaristos Amalia N. Miliou Antonios N. Anagnostopoulos Antanas Čenys 《Nonlinear Analysis: Theory, Methods & Applications》2008
The dynamic behaviour of the one-dimensional family of maps f(x)=c2[(a−1)x+c1]−λ/(α−1) is examined, for representative values of the control parameters a,c1, c2 and λ. The maps under consideration are of special interest, since they are solutions of the relaxed Newton method derivative being equal to a constant a. The maps f(x) are also proved to be solutions of a non-linear differential equation with outstanding applications in the field of power electronics. The recurrent form of these maps, after excessive iterations, shows, in an xn versus λ plot, an initial exponential decay followed by a bifurcation. The value of λ at which this bifurcation takes place depends on the values of the parameters a,c1 and c2. This corresponds to a switch to an oscillatory behaviour with amplitudes of f(x) undergoing a period doubling. For values of a higher than 1 and at higher values of λ a reverse bifurcation occurs. The corresponding branches converge and a bleb is formed for values of the parameter c1 between 1 and 1.20. This behaviour is confirmed by calculating the corresponding Lyapunov exponents. 相似文献
50.
Inactivation effect of an electric current treatment combining both 188 μA/m2 DC and 251 μA/m2 AC on Gram negative, Gram positive bacteria and their mixed culture, which were isolated from hides, was separately analyzed. This electric treatment, applied for 16 min was found to be fairly effective in reducing the bacterial cell count (7.10–7.48 log10 colony forming units/mL) to a relatively low level (4.52–4.90 log10 colony forming units/mL). At this level bacterial damage to the hides is reduced in soak liquors. Cheap and efficient electric current may be applied to rapidly reduce the destructive bacterial populations in main hide-soak liquors. 相似文献