Reactions最新文献_第7页

The First Step and the Cob(II)alamin Cofactor Inactive Particles Reactivation in the Updated Mechanism of the Methionine Synthase Process 蛋氨酸合酶过程的第一步和Cob(II)alamin辅因子失活颗粒再激活的最新机制

Reactions Pub Date : 2023-05-22 DOI: 10.3390/reactions4020016

T. Spataru

{"title":"The First Step and the Cob(II)alamin Cofactor Inactive Particles Reactivation in the Updated Mechanism of the Methionine Synthase Process","authors":"T. Spataru","doi":"10.3390/reactions4020016","DOIUrl":"https://doi.org/10.3390/reactions4020016","url":null,"abstract":"The Methionine Synthase process, in principle, can take an unlimited number of turnovers in the presence of the AdoMet substrate. In the absence of this substrate, the Methionine Synthase process lasts only about 2000 turnovers. During 2000 turnovers, the entire amount of methylcob(II)alamin cofactor is converted into inactive cob(II)alamin particles. Nevertheless, the mechanism of the Methionine Synthase process determined previously lacks the presence of the AdoMet substrate. On the other hand, the first step of this mechanism was only mentioned earlier without its analysis. The CASSCF geometry optimization of the inactive cob(II)alamin cofactor particle plus the AdoMet ion substrate and of the methylcob(II)alamin cofactor particle plus homocysteine ion and histidine molecule joint models have been performed. CASSCF calculations show that the AdoMet particle transfers the methyl radical to the biologically inactive cob(II)alamin particle during their interaction, transforming it into the biologically active particle of methylcob(II)alamin. CASSCF geometry optimization of the second model leads to the Co-N bond’s full cleavage. The two processes take place in the absence of the total energy barrier. The fully updated mechanism of the Methionine Synthase process has been drawn.","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79066638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hemetsberger–Knittel and Ketcham Synthesis of Heteropentalenes with Two (1:1), Three (1:2)/(2:1) and Four (2:2) Heteroatoms 二(1:1)、三(1:2)/(2:1)和四(2:2)杂原子杂戊烯的Hemetsberger-Knittel和Ketcham合成

Reactions Pub Date : 2023-05-08 DOI: 10.3390/reactions4020015

Z. Tokárová, R. Gašparová, Natalia M. Kabanova, Marcela Gašparová, R. Balogh

{"title":"Hemetsberger–Knittel and Ketcham Synthesis of Heteropentalenes with Two (1:1), Three (1:2)/(2:1) and Four (2:2) Heteroatoms","authors":"Z. Tokárová, R. Gašparová, Natalia M. Kabanova, Marcela Gašparová, R. Balogh","doi":"10.3390/reactions4020015","DOIUrl":"https://doi.org/10.3390/reactions4020015","url":null,"abstract":"The synthetic methods leading to furo[3,2-b]pyrroles and thiazolo [5,4-d]thiazoles are reviewed herein. Furo-, thieno- and seleno [3,2-b]pyrroles are related to heteropentalenes, containing two heteroatoms in the entire structure, one each per core. The synthetic approach follows the Hemetsberger–Knittel protocol covering three reaction steps—the nucleophilic substitution of halogen-containing aliphatic carboxylic acid esters, Knoevenagel condensation and, finally, thermolysis promoting the intramolecular cyclocondensation to O,N-heteropentalene. The Hemetsberger–Knittel reaction sequence is also known for the preparation of O,N-heteropentalenes with three heteroatoms (2:1) and their sulphur and selen heteroatoms containing structural analogues and bispyrroles. The synthetic approach towards thiazolo [5,4-d] thiazoles represents a more straightforward route, according to the Ketcham cyclocondensation. Proceeding with the Ketcham process is more challenging since it occurs stepwise and the formation of by-products is obvious. Thiazolo [5,4-d]thiazole is a representative of the aromatic heteropentalene with four heteroatoms in the structure—twinned N and S, two for each of the five-membered rings. The synthetic approaches towards those particular heteropentalnes have been chosen as a consequence of our ongoing research dealing with the design, synthesis and applications of substituted furo [3,2-b]pyrroles and thiazolo [5,4-d]thiazole-based derivatives. While the furopyrroles are known for their pharmacological activity, thiazolothiazoles have become of interest to materials science. We are aware that from a “bank” of existing compounds/procedures not all are presented in this review, and we apologise to respective groups whose research have not been objectively included.","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85586427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhancing Photon Transfer Efficiency in Photocatalysis Using Suspended LED Lights for Water Treatment 利用悬浮式LED灯提高光催化中的光子传递效率

Reactions Pub Date : 2023-04-18 DOI: 10.3390/reactions4020014

Samira Mosalaei Rad, A. Ray, S. Barghi

{"title":"Enhancing Photon Transfer Efficiency in Photocatalysis Using Suspended LED Lights for Water Treatment","authors":"Samira Mosalaei Rad, A. Ray, S. Barghi","doi":"10.3390/reactions4020014","DOIUrl":"https://doi.org/10.3390/reactions4020014","url":null,"abstract":"Photocatalysis application in water treatment has been the object of many researchers worldwide in recent decades. However, there are limited commercial applications due to low photon transfer efficiency, which create barriers leading to challenges in making the process efficient and economically feasible. Fixed UV/visible light sources, which are generally located outside the reactor or encapsulated in quartz tube inside the reactor are the source of energy to activate photocatalyst generating powerful oxidants such as electrons and holes. Suspended waterproof LED visible lights were employed to enhance photon transfer efficiency. Consequently, the required energy was lower resulting in negligible temperature increase and eliminated the need for an external cooler, no need for quartz (UV transparent) or treated glass reactors, enhanced mixing due to continuous movement of light bulbs by convective currents, and minimum/no attenuation. Direct Blue 15 (DB15) dye was used as model compound and the photocatalyst was P25 TiO2 (Average particle: 30 nm, Surface area: 50 m2 g−1). The samples taken at different time intervals were analyzed by UV-Vis. spectrophotometer (UV-3600), and TOC-V CPN total organic carbon analyzer (both from Shimadzu). It was found that for the same level of degradation, the degradation rate increased by about 50% compared to conventional fixed light photoreactor. Overall, the cost of the operation can be reduced substantially, paving the road for feasible commercialization of the process.","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76548294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Biocatalytic Profiling of Free and Immobilized Partially Purified Alkaline Protease from an Autochthonous Bacillus aryabhattai Ab15-ES 原生芽孢杆菌Ab15-ES游离和固定化部分纯化碱性蛋白酶的生物催化分析

Reactions Pub Date : 2023-04-03 DOI: 10.3390/reactions4020013

Adegoke Isiaka Adetunji, A. Olaniran

{"title":"Biocatalytic Profiling of Free and Immobilized Partially Purified Alkaline Protease from an Autochthonous Bacillus aryabhattai Ab15-ES","authors":"Adegoke Isiaka Adetunji, A. Olaniran","doi":"10.3390/reactions4020013","DOIUrl":"https://doi.org/10.3390/reactions4020013","url":null,"abstract":"Partially purified alkaline protease produced by an indigenous bacterial strain, Bacillus aryabhattai Ab15-ES, was insolubilized in alginate beads using an entrapment technique. Maximum entrapped enzyme activities of 68.76% and 71.06% were recorded at optimum conditions of 2% (w/v) sodium alginate and 0.3 M calcium chloride. Biochemical profiling of free and immobilized proteases was investigated by determining their activity and stability as well as kinetic properties. Both enzyme preparations exhibited maximum activity at the optimum pH and temperature of 8.0 and 50 °C, respectively. However, in comparison to the free enzyme, the immobilized protease showed improved pH stability at 8.0–9.0 and thermal stability at 40–50 °C. In addition, the entrapped protease exhibited a higher Vmax and increased affinity to the substrate (1.65-fold) than the soluble enzyme. The immobilized protease was found to be more stable than the free enzyme, retaining 80.88% and 38.37% of its initial activity when stored at 4 °C and 25 °C, respectively, for 30 d. After repeated use seven times, the protease entrapped in alginate beads maintained 32.93% of its original activity. These findings suggest the efficacy and sustainability of the developed immobilized catalytic system for various biotechnological applications.","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78865798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

BCG vaccine 卡介苗

Reactions Pub Date : 2023-04-01 DOI: 10.1007/s40278-023-37930-x

引用次数: 0

Visible Light Induced C-H/N-H and C-X Bonds Reactions 可见光诱导的C-H/N-H和C-X键反应

Reactions Pub Date : 2023-03-02 DOI: 10.3390/reactions4010012

M. Ahmad, Po-han Lin, Qing Zhang, Bing Zeng, Qifeng Wang, K. Meguellati

引用次数: 0

UV/VIS-Spectroscopic Inline Measurement for the Detection of Fouling Processes during the Polymerization of N-Vinylpyrrolidone 紫外/可见光谱在线检测n -乙烯基吡咯烷酮聚合过程中的污垢

Reactions Pub Date : 2023-03-01 DOI: 10.3390/reactions4010011

Erik Spoor, S. Welzel, U. Nieken, M. Rädle

引用次数: 0

Initial Steps in the Reaction of H2O2 with Fe2+ and Fe3+ Ions: Inconsistency in the Free Radical Theory H2O2与Fe2+和Fe3+离子反应的初始步骤:自由基理论的不一致性

Reactions Pub Date : 2023-02-20 DOI: 10.3390/reactions4010010

M. L. Kremer

引用次数: 1

Behavior of Premixed Sooting Flame in a High-Pressure Burner 高压燃烧器中预混合烟尘火焰的特性

Reactions Pub Date : 2023-02-02 DOI: 10.3390/reactions4010009

A. Saylam

{"title":"Behavior of Premixed Sooting Flame in a High-Pressure Burner","authors":"A. Saylam","doi":"10.3390/reactions4010009","DOIUrl":"https://doi.org/10.3390/reactions4010009","url":null,"abstract":"The second-order factor effect of burner optical ports and edge inter-matrices (EIM) and the first-order factor of pressure on the soot formation process and behavior of premixed sooting flames in a high-pressure burner are numerically investigated here. Three-dimensional computational fluid dynamics (CFD) simulations of a premixed flame C2H4/air at p = 1.01 and 10 bar using a one-step chemistry approach are first performed to justify the satisfied predictability of the prospective axisymmetric two-dimensional (2D) and one-dimensional (1D) simulations. The justified 2D simulation approach shows the generation of an axial vorticity around the EIM and axial multi-vorticities due to the high expansion rate of burnt gases at the high pressure of 10 bar. This leads to the development of axial multi-sooting zones, which are manifested experimentally by visible luminous soot streaks, and to the boosting of soot formation conditions of a relatively low-temperature field, <1800 K, and a high mixing rate of gases in combustion around and above the EIM location. Nevertheless, a tolerable effect on the centerline soot volume fraction (fV) profile, fV < 3%, is manifested only at high heights above the burner of the atmospheric sooting flame C2H4/air ϕ = 2.1, and early at the high pressure of 10 bar of this flame, fV < 10%. Enhancing the combustion process reactivity by decreasing the rich equivalence ratio of the fuel/air mixture and/or rising the pressure results in the prior formation of soot precursors, which shifts the sooting zone upstream.","PeriodicalId":20873,"journal":{"name":"Reactions","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88964890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Simple Way to Obtain a Decachloro Derivative of Cobalt Bis(dicarbollide) 一种简单制备二碳内酯钴十氯衍生物的方法

Reactions Pub Date : 2023-02-01 DOI: 10.3390/reactions4010008

Sergey A. Anufriev, M. Stogniy, I. Sivaev

引用次数: 0