Kinetic Investigation of Consecutive-Parallel Reactions in the Non-Catalytic Process of Ethylene Oxide Hydrolysis

2004 ◽  
Vol 15 (1) ◽  
pp. 19-31
Author(s):  
MARWAN BATIHA
Keyword(s):  
Ethylene Oxide ◽  
Catalytic Process ◽  
Kinetic Investigation ◽  
Parallel Reactions

THE SILVER CATALYZED OXIDATION OF ETHYLENE: IV. REACTION MECHANISM

1954 ◽  
Vol 32 (4) ◽  
pp. 443-451 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Reaction Mechanism ◽  
Ethylene Oxide ◽  
Temperature Dependent ◽  
Heterogeneous Oxidation ◽  
Initial Oxidation ◽  
Partial Pressures ◽  
Parallel Reactions ◽  
Single Oxygen ◽  
Catalyzed Oxidation ◽  
Adsorbed Ethylene

A reaction mechanism for the silver catalyzed oxidation of C2H4 by oxygen has been formulated which is consistent with kinetic data for this system. It is suggested that both ethylene oxide and CO2 formation involve interaction of single gaseous C2H4 molecules with single oxygen adatoms. This may be a system of two parallel reactions of different activation energy requirements or a common initiation step to form adsorbed ethylene oxide which may then desorb immediately or isomerize to acetaldehyde followed by rapid oxidation to CO2 and H2O. Account is taken of the known adsorption characteristics of O2 on silver to deduce expressions for initial rates of ethylene oxide and CO2 formation as a function of reactant partial pressures. The generalized form of the equation is r = k(1 + a/pE + b/pO)−1, where k, a, and b are temperature dependent constants and pE and pO are partial pressures of ethylene and of oxygen respectively.A mechanism is also suggested for the heterogeneous oxidation of ethylene oxide which involves interaction between a gas phase ethylene oxide molecule and a single oxygen adatom to form an intermediate (probably formaldehyde) which is rapidly oxidized to CO2 and H2O. A similar expression to that above for the initial oxidation rate is deduced. These expressions have been fitted successfully to experimental data.

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1

2019 ◽  
Vol 476 (21) ◽  
pp. 3227-3240 ◽  
Author(s):  
Shanshan Wang ◽  
Yanxiang Zhao ◽  
Long Yi ◽  
Minghe Shen ◽  
Chao Wang ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Conformational Changes ◽  
Magnaporthe Oryzae ◽  
Structural Information ◽  
Complex Structure ◽  
Critical Role ◽  
Catalytic Process ◽  
Structural Basis ◽  
Salt Bridges ◽  
Terminal Domain

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.

Comparative analysis of polymorphic variants of IL-17A and MMP-1 genes with the risk of developing chronic periodontitis in petrochemical workers

2020 ◽  
Vol 60 (10) ◽  
pp. 687-693
Author(s):  
Iskander I. Zaidullin ◽  
Denis O. Karimov ◽  
Lilija K. Karimova ◽  
Milyausha F. Kabirova ◽  
Rasima R. Galimova ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Chronic Periodontitis ◽  
Periodontal Diseases ◽  
Clinical Manifestations ◽  
Control Group ◽  
Periodontal Tissues ◽  
Dental Examination ◽  
Number Of Patients ◽  
Increased Risk ◽  
Harmful Substances

The susceptibility to the development and progression of inflammatory periodontal diseases, which depends on genetic and external factors (smoking, stress, oral hygiene), varies widely. In the development of these diseases, an important role is played not only by the presence of periodontal pathogenic microorganisms, but also by the presence of congenital or acquired immunodeficiency, immunoregulatory defects. The immune system plays a key role in the physiological and pathological processes of periodontal tissues. In this regard, IL17, produced by CD4+ Th cells, which has both Pro-inflammatory and protective activity, is of particular interest in the pathogenesis of periodontitis. The aim of study was to identify the relationship between polymorphic loci of the IL-17A (rs2275913) and MMP-1 (rs1799750) genes and clinical manifestations of chronic periodontitis in petrochemical workers. Dental examination was performed in 92 ethylene oxide production workers with chronic periodontitis and 74 patients with chronic periodontitis who did not come into contact with chemical factors (control group). Genotyping of polymorphisms rs2275913 of the IL17A gene and rs1799750 of the MMP1 gene was performed by allele-specific real-time polymerase chain reaction (PCR). Hygienic assessment of the degree of air pollution of the working area with harmful substances was carried out by gas chromatography according to the guidelines for the determination of harmful substances in the air № 5098-89, № 3119-84. When comparing the results of studies of both groups, there were no statistically significant differences in the frequency distributions of allelic variants and genotypes of the IL-17A and MMP-1 genes. The AA/AG genotypes of the IL-17A gene were associated with an increased risk of severe disease compared to the GG genotype in workers in the main group (OR=6.1; 95% CI 1.33-28.5; p=0.021) and in the control group (OR=7.26; 95% CI 1.34-39.25; p=0.016). Carriers of the A allele in the control group increased the risk of severe chronic periodontitis by 2.4 times compared to carriers of the G allele (OR=2.41; 95% CI 1.19-4.87; p=0.014). During the dental examination of employees of the ethylene oxide plant, the clinical course of periodontal diseases was more severe in comparison with the control group, and the number of patients with severe periodontitis was twice as high. It was found that the AA/AG genotypes of the IL-17A gene and the carrier of the A allele are associated with increased susceptibility to the development of severe chronic periodontitis. The association between the MMP-1 gene polymorphism and the risk of severe forms of chronic periodontitis has not been established. A risk factor for the development of inflammatory periodontal diseases in employees of the petrochemical complex is a complex of harmful production factors.

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