elimination mechanism
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2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dmitrii Sliadovskii ◽  
Tatyana Ponomareva ◽  
Maxim Molchanov ◽  
Irina Pozdnyakova-Filatova ◽  
Maria Timchenko ◽  
...  

AbstractCrustacean hyaluronidases are poorly understood both in terms of their enzymatic properties and in terms of their structural features. In this work, we show that the hepatopancreas homogenate of the red king crab has a hyaluronidase activity that is an order of magnitude higher than its commercial counterpart. Zymography revealed that the molecular weight of a protein with hyalorunidase activity is 40–50 kDa. Analysis of the hepatopancreas transcriptome and results of cloning and sequencing of cDNA revealed a hyaluronidase sequence with an expected molecular weight of 42.5 kDa. Further analysis showed that hyaluronat enzymatic cleavage follows the $$\beta $$ β -elimination mechanism, which is well known for bacterial hyaluronidases. The results of ion-exchange chromatography showed that the final product of hyaluronate degradation is unsaturated tetrasaccharide. Thus, we identified a new hyaluronidase of higher eukaryotes, which is not integrated into the modern classification of hyaluronidases.


2021 ◽  
Author(s):  
◽  
Struan John Wright Cummins

<p>In the present study, synthetic routes to formal double bonds between gallium and carbon (fig 1), nitrogen (fig 2), and phosphorus (fig 3) have been investigated. These synthetic routes utilised the monoanionic, four electron donor, β-diketiminate (BDI) ligand to provide both steric and electronic stabilisation to three coordinate gallium complexes. The known di-substituted β-diketiminatogallium complexes: [(BDI)GaMe₂] and [(BDI)Ga(NHPh)₂], as well the new complexes: [(BDI)GaBn₂], [(BDI)Ga(NHDMP)₂] (DMP = 2,6-Me₂C₆H₃), [(BDI)Ga(NHDIPP)₂] (DIPP = 2,6-iPr₂C₆H₃), [(BDI)Ga(PHPh)₂] were examined for their reactivity towards the α-proton elimination mechanism for the formation of multiple bonds that is observed in transition metals. All of these complexes were shown to be unreactive towards α-proton elimination.  The di-substituted β-diketiminato-gallium complex [(BDI)GaMe₂] was subjected to various aniline derivatives to investigate if the methyl ligands exhibited the same reactivity as di-methyl transition metal complexes, where the methyl ligands could deprotonate the aniline to form a metal-imido complex. This complex was found to have no reactivity with anilines.  The mono-substituted β-diketiminato-gallium complex [(BDI)Ga(NHDMP)Cl] was tested for its reactivity with ⁿBuLi to abstract the amide proton and eliminate LiCl to form a gallium imido complex. While the ¹H NMR spectrum of the reaction mixture showed that a reaction had occurred, the products could not be isolated for characterisation.  Another mono-substituted β-diketiminato-gallium complex [(BDI)Ga(PHPh)Cl] was also tested for its reactivity with ⁿBuLi to abstract the phosphide proton and eliminate LiCl to form a gallium phosphinidene complex. The ¹H NMR spectrum and ³¹P NMR spectrum of the isolated complex revealed that it still contained a phosphide proton, however the gallium centre now appeared to be bonded to a former methine carbon of an isopropyl group of the BDI ligand (fig 32). This bond may have formed through metathesis between an intermediate containing a gallium-phosphorus double bond, and the C-H bond of the isopropyl group. Further mechanistic studies could confirm if an intermediate such as [fig 3] is formed, and the synthetic strategy altered to isolate it.  The synthesis of β-diketiminato-gallium-alkoxide complexes was also attempted, however the products of these synthesises could not be isolated due to solubility issues, potentially due to polymerisation.</p>


2021 ◽  
Author(s):  
◽  
Struan John Wright Cummins

<p>In the present study, synthetic routes to formal double bonds between gallium and carbon (fig 1), nitrogen (fig 2), and phosphorus (fig 3) have been investigated. These synthetic routes utilised the monoanionic, four electron donor, β-diketiminate (BDI) ligand to provide both steric and electronic stabilisation to three coordinate gallium complexes. The known di-substituted β-diketiminatogallium complexes: [(BDI)GaMe₂] and [(BDI)Ga(NHPh)₂], as well the new complexes: [(BDI)GaBn₂], [(BDI)Ga(NHDMP)₂] (DMP = 2,6-Me₂C₆H₃), [(BDI)Ga(NHDIPP)₂] (DIPP = 2,6-iPr₂C₆H₃), [(BDI)Ga(PHPh)₂] were examined for their reactivity towards the α-proton elimination mechanism for the formation of multiple bonds that is observed in transition metals. All of these complexes were shown to be unreactive towards α-proton elimination.  The di-substituted β-diketiminato-gallium complex [(BDI)GaMe₂] was subjected to various aniline derivatives to investigate if the methyl ligands exhibited the same reactivity as di-methyl transition metal complexes, where the methyl ligands could deprotonate the aniline to form a metal-imido complex. This complex was found to have no reactivity with anilines.  The mono-substituted β-diketiminato-gallium complex [(BDI)Ga(NHDMP)Cl] was tested for its reactivity with ⁿBuLi to abstract the amide proton and eliminate LiCl to form a gallium imido complex. While the ¹H NMR spectrum of the reaction mixture showed that a reaction had occurred, the products could not be isolated for characterisation.  Another mono-substituted β-diketiminato-gallium complex [(BDI)Ga(PHPh)Cl] was also tested for its reactivity with ⁿBuLi to abstract the phosphide proton and eliminate LiCl to form a gallium phosphinidene complex. The ¹H NMR spectrum and ³¹P NMR spectrum of the isolated complex revealed that it still contained a phosphide proton, however the gallium centre now appeared to be bonded to a former methine carbon of an isopropyl group of the BDI ligand (fig 32). This bond may have formed through metathesis between an intermediate containing a gallium-phosphorus double bond, and the C-H bond of the isopropyl group. Further mechanistic studies could confirm if an intermediate such as [fig 3] is formed, and the synthetic strategy altered to isolate it.  The synthesis of β-diketiminato-gallium-alkoxide complexes was also attempted, however the products of these synthesises could not be isolated due to solubility issues, potentially due to polymerisation.</p>


2021 ◽  
pp. 110225
Author(s):  
Yuchang Zhi ◽  
Jiemin Zhan ◽  
Renfang Huang ◽  
Rundi Qiu ◽  
Yiwei Wang

Author(s):  
Li Su ◽  
Feng Chen ◽  
Huahang Yu ◽  
Hao Yan ◽  
Fengjiao Zhao ◽  
...  

Author(s):  
Shuai Zhao ◽  
Guodong Yuan ◽  
Di Zhang ◽  
Pengfei Xu ◽  
Guozheng Li ◽  
...  

2021 ◽  
pp. 096739112110375
Author(s):  
Fawzi H Jabrail ◽  
Hiba M Awad ◽  
Abdulsalam A Matlob

The wet treatment process was used for the dechlorination of poly(vinyl chloride) (PVC) landfill waste plastic, and the process has shown dependence on concentration of alkali. The process of dechlorination of PVC has shown dependence on the concentration of the alkaline solution and the type of organic solvent used in the preparation of the alkaline solution. Ethylene glycol (EG), diethylene glycol (DEG), and tetraethylene glycol (TEG) are the diols that have been investigated. Moreover, the temperature of the PVC dechlorination process and the time of the PVC solution reflux showed effects on the final degree of the dechlorination (DD%). These were calculated using the Mohr method, where the chloride ions were titrated with a standard solution of silver nitrate in the presence of chromate ions. The study shows that 1 M NaOH/TEG alkaline solution was the best to dechlorinate PVC waste with the wet treatment process at 160 ̊c and for 3 h reflux and the process reclaimed poly(vinyl alcohol) PVA as the main product according to the hydroxyl group substitution mechanism (SN2), besides a few units according to the hydrogen chloride elimination mechanism (E2) with a few remaining chlorinated chains after analysis.


Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yiguang Pan ◽  
Xiaomei Deng

The rise of blockchain has led to discussions on new governance models and the cooperation of multiple participants. Due to the cognitive defects of the blockchain protocol in terms of intelligent contracts and decentralized autonomous organizations (DAOs), it is often unclear as to how to make decisions about the evolution of blockchain applications. Many autonomous organizations, with the support of network technologies such as blockchain, blindly absorb members and expand the scale of the capital pool, while ignoring the cost advantage of traditional autonomous organizations based on social relations and mutual supervision to fight information asymmetry. In this context, this study analyzes the evolutionary trend of autonomous organizations and their members’ strategies under different policy environments. To this end, under the digital economy background, based on game theory, the evolutionary dynamics method, and the form of the mutual insurance organization, this study constructs an evolutionary dynamics model of distributed autonomous organizations. The results show that blind expansion without review aggravates the overall risk pool’s moral hazard, in the context of mutual insurance. Organizational strategies, such as risk pool splits, can effectively improve the risk pool’s operating performance and establish a benign competition elimination mechanism. Driven by cooperation efficiency and split supervision based on homogeneous clustering, the comprehensive application of the market elimination mechanism can effectively combat moral hazards, restrain the adverse effects of member flow, expand the living space of small- and medium-sized insurance organizations, curb the emergence of a large-scale monopoly risk pool, and improve market vitality. These conclusions and suggestions also apply to autonomous organizations based on social relations and mutual supervision. The results offer specific decision-making guidance and suggestions for the government, insurance companies, and risk management.


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