scholarly journals Phosphorylation of Cellulose in the Presence of Urea. Mechanism of Reaction and Reagent Impact.

2021 ◽  
Author(s):  
Dan Belosinschi ◽  
Abdelhaq Benkaddour ◽  
Bogdan-Marian Tofanica ◽  
TriDung Ngo
Keyword(s):  
Thermal Stability ◽  
Phosphoric Acid ◽  
Limiting Factor ◽  
Cellulose Phosphate ◽  
Mechanism Of Reaction ◽  
Phosphate Species ◽  
Reactive Mixture ◽  
Urea Decomposition ◽  
Thermal Stability Of

Abstract A mechanism of cellulose phosphorylation in presence of urea is proposed. This model is correlated with the thermal stability of phosphorylating reactive mixture and the yield of phosphorylation for two different reagents: phosphoric acid and lauryl phosphate monoester. Three main successive reactions are involved in the formation of cellulose phosphate: (1) generation of ammonia by urea decomposition, (2) formation of phosphoramidate as intermediate reactive due to the reaction of ammonia with phosphate species, and (3) grafting the phosphate moiety to substrate due to the transfer of phosphate from phosphoramidate to cellulose. The proposed in vitro mechanism is supported by similar phosphorylation processes observed in some biochemical reactions. The limiting factor in the phosphorylation of cellulose is the formation of phosphoramidate intermediate.

scholarly journals STUDY OF THERMAL DECOMPOSITION PRODUCTS OF NITROGEN-PHOSPHORUS-POTASSIUM FERTILIZERS BASED ON AMMONIUM NITRATE BY X-RAY DIFFRACTUON

2017 ◽  
Vol 61 (1) ◽  
pp. 72
Author(s):  
Konstantin G. Gorbovskiy ◽  
Alena S. Ryzhova ◽  
Andrey M. Norov ◽  
Denis A. Pagaleshkin ◽  
Valentina N. Kalinina ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Phosphoric Acid ◽  
Ammonium Nitrate ◽  
Confined Space ◽  
Decomposition Products ◽  
X Ray ◽  
Thermal Decomposition Products ◽  
Nitrogen Phosphorus ◽  
Thermal Stability Of

Complex mineral ammonium nitrate-based fertilizers are complex multicomponent salt systems possessing low thermal stability and prone to self-sustaining decomposition. This leads to the need to increase the requirements for fire and explosion safety in their manufacture, storage and transportation, caused by the fact that ammonium nitrate is a solid oxidant able to support a combustion, and its heating in confined space can lead to detonation. Components that make up such fertilizers can both reduce (phosphates and ammonium sulfate) and accelerate (chlorine compounds) decomposition of ammonium nitrate. Thus, the thermal stability of fertilizers based on ammonium nitrate largely depends on the ratio of the components that make up its composition or formed as a result of the chemical reaction. The simplest way to reduce the content of ammonium nitrate and increase the thermal stability of fertilizer without changing the content of essential nutrients is to increase the degree of phosphoric acid ammoniation. In this paper, the phase composition change of grade 22:11:11 nitrogen-phosphorus-potassium fertilizer obtained with different ammoniation degree in the process of thermal decomposition was studied by X-ray phase analysis. To obtain this fertilizer, wet-process phosphoric acid obtained sulfuric acid attack of the Khibin apatite concentrate by a hemihydrate method is used. It is shown that an increase in the ammoniation degree has a significant effect on the exothermic decomposition of ammonium nitrate and the amount of material that is released into the gas phase. The phases formed at each stage of the decomposition are determined.Forcitation:Gorbovskiy K.G., Ryzhova A.S., Norov A.M., Pagaleshkin D.A., Kalinina V.N., Mikhaylichenko A.I. Study of thermal decomposition products of nitrogen-phosphorus-potassium fertilizers based on ammonium nitrate by X-ray diffractuon. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 72-77

scholarly journals A Possible Mechanism of Graphene Oxide to Enhance Thermostability of D-Psicose 3-Epimerase Revealed by Molecular Dynamics Simulations

2021 ◽  
Vol 22 (19) ◽  
pp. 10813
Author(s):  
Congcong Li ◽  
Zhongkui Lu ◽  
Min Wang ◽  
Siao Chen ◽  
Lu Han ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Thermal Stability ◽  
Graphene Oxide ◽  
Md Simulations ◽  
Strong Interactions ◽  
Limiting Factor ◽  
Active Site Residues ◽  
Detailed Mechanism ◽  
Dynamics Simulations ◽  
Thermal Stability Of

Thermal stability is a limiting factor for effective application of D-psicose 3-epimerase (DPEase) enzyme. Recently, it was reported that the thermal stability of DPEase was improved by immobilizing enzymes on graphene oxide (GO) nanoparticles. However, the detailed mechanism is not known. In this study, we investigated interaction details between GO and DPEase by performing molecular dynamics (MD) simulations. The results indicated that the domain (K248 to D268) of DPEase was an important anchor for immobilizing DPEase on GO surface. Moreover, the strong interactions between DPEase and GO can prevent loop α1′-α1 and β4-α4 of DPEase from the drastic fluctuation. Since these two loops contained active site residues, the geometry of the active pocket of the enzyme remained stable at high temperature after the DPEase was immobilized by GO, which facilitated efficient catalytic activity of the enzyme. Our research provided a detailed mechanism for the interaction between GO and DPEase at the nano–biology interface.

In silico and in vitro Approaches to Elucidate the Thermal Stability of Human UDP-glucuronosyltransferase (UGT) 1A9

2009 ◽  
Vol 24 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Ryoichi Fujiwara ◽  
Miki Nakajima ◽  
Tetsunori Yamamoto ◽  
Hidemi Nagao ◽  
Tsuyoshi Yokoi
Keyword(s):  
Thermal Stability ◽  
In Silico ◽  
Udp Glucuronosyltransferase ◽  
Thermal Stability Of

Effects of glycine betaine and glycerophosphocholine on thermal stability of ribonuclease

1998 ◽  
Vol 274 (4) ◽  
pp. F762-F765 ◽  
Author(s):  
Maurice B. Burg ◽  
Eugenia M. Peters
Keyword(s):  
Thermal Stability ◽  
Tissue Culture ◽  
Glycine Betaine ◽  
Metabolic Cost ◽  
Rnase A ◽  
Renal Cells ◽  
And Function ◽  
Thermal Stability Of

Urea in renal medullas is sufficiently high to perturb macromolecules, yet the cells survive and function. The counteracting osmolytes hypothesis holds that methylamines, such as glycine betaine (betaine) and glycerophosphocholine (GPC) in renal medullas, stabilize macromolecules and oppose the effects of urea. Although betaine counteracts effects of urea on macromolecules in vitro and protects renal cells from urea in tissue culture, renal cells accumulate GPC rather than betaine in response to high urea both in vivo and in tissue culture. A proposed explanation is that GPC counteracts urea more effectively than betaine. However, we previously found GPC slightly less effective than betaine in counteracting inhibition of pyruvate kinase activity by urea. To test another macromolecule, we now compare GPC and betaine in counteracting reduction of the thermal stability of RNase A by urea. We find that urea decreases the thermal transition temperature and that betaine and GPC increase it, counteracting urea approximately equally. Therefore, the preference for GPC in response to high urea presumably has some other basis, such as a lower metabolic cost of GPC accumulation.

Synthesis and investigation of in vitro cytotoxic activities and thermal stability of novel pyridine derivative platinum (II) complexes vis a vis DFT studies

Polyhedron ◽  
2021 ◽  
pp. 115492
Author(s):  
Emine Kutlu ◽  
Fatih Mehmet Emen ◽  
Görkem Kismali ◽  
Neslihan Kaya Kınaytürk ◽  
Ali Ihsan Karacolak ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Pyridine Derivative ◽  
Cytotoxic Activities ◽  
Dft Studies ◽  
Thermal Stability Of

scholarly journals THE THERMAL STABILITY OF RHODOPSIN AND OPSIN

1958 ◽  
Vol 42 (2) ◽  
pp. 259-280 ◽  
Author(s):  
Ruth Hubbard
Keyword(s):  
Thermal Stability ◽  
Thermal Denaturation ◽  
Species Differences ◽  
Activation Energies ◽  
Specific Relationship ◽  
Thermal Bleaching ◽  
Thermal Stability Of ◽  
Cis Isomer

Rhodopsin, the red photosensitive pigment of rod vision, is composed of a specific cis isomer of retinene, neo-b (11-cis), joined as chromophore to a colorless protein, opsin. We have investigated the thermal denaturation of cattle rhodopsin and opsin in aqueous digitonin solution, and in isolated rod outer limbs. Both rhodopsin and opsin are more stable in rods than in solution. In solution as well as in rods, moreover, rhodopsin is considerably more stable than opsin. The chromophore therefore protects opsin against denaturation. This is true whether rhodopsin is extracted from dark-adapted retinas, or synthesized in vitro from neo-b retinene and opsin. Excess neo-b retinene does not protect rhodopsin against denaturation. The protection involves the specific relationship between the chromophore and opsin. Similar, though somewhat less, protection is afforded opsin by the stereoisomeric iso-a (9-cis) chromophore in isorhodopsin. The Arrhenius activation energies (Ea) and entropies of activation (ΔS‡) are much greater for thermal denaturation of rhodopsin and isorhodopsin than of opsin. Furthermore, these values differ considerably for rhodopsins from different species —frog, squid, cattle—presumably due to species differences in the opsins. Heat or light bleaches rhodopsin by different mechanisms, yielding different products. Light stereoisomerizes the retinene chromophore; heat denatures the opsin. Photochemical bleaching therefore yields all-trans retinene and native opsin; thermal bleaching, neo-b retinene and denatured opsin.

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