Pub Date : 2024-05-17DOI: 10.3389/fctls.2024.1353746
Tobias Schanz, Markus Stöckl, Bastien O. Burek, Dirk Holtmann, Jonathan Z. Bloh
In recent years, the electrochemical synthesis of peroxides has attracted renewed interest as a potential environmentally friendly production compared to the established anthraquinone process. In addition, it is possible to produce the peroxides directly on site, eliminating the need for expensive and hazardous transportation and storage. Cathodic production of hydrogen peroxide from oxygen is already quite well developed. Anodic production from water, on the other hand, is still facing significant challenges, despite its historic pioneering role. In this manuscript we show that anodic and cathodic synthesis of peroxides can even be combined to achieve greater than 100% current efficiency (CE) due to the combined effect of both half-reactions. So far, similar devices have always employed different electrolytes for each, which necessitated the use of a membrane and posed contamination risk. However, herein we show that both half-reactions can also employ the same electrolyte. This enables even an undivided cell, omitting the need for the expensive membranes. Despite its simplicity, this setup yielded an outstanding performance with a combined CE of 144%.
近年来，过氧化物的电化学合成作为一种潜在的环境友好型生产工艺，与已有的蒽醌工艺相比，再次引起了人们的兴趣。此外，过氧化物可以直接在现场生产，无需昂贵而危险的运输和储存。利用氧气进行阴极法生产过氧化氢的技术已经相当成熟。另一方面，从水中阳极制取过氧化氢尽管具有历史性的先驱作用，但仍然面临着巨大的挑战。在本手稿中，我们展示了过氧化物的阳极和阴极合成甚至可以结合使用，由于两种半反应的共同作用，电流效率（CE）甚至可以超过 100%。迄今为止，类似的装置总是各自使用不同的电解质，这就需要使用膜并带来污染风险。然而，我们在本文中展示了两种半反应也可以使用相同的电解质。这样，即使是不分割的电池，也无需使用昂贵的膜。尽管结构简单，但这一装置却能产生出色的性能，综合 CE 值高达 144%。
{"title":"Combined anodic and cathodic peroxide production in an undivided carbonate/bicarbonate electrolyte with 144% combined current efficiency","authors":"Tobias Schanz, Markus Stöckl, Bastien O. Burek, Dirk Holtmann, Jonathan Z. Bloh","doi":"10.3389/fctls.2024.1353746","DOIUrl":"https://doi.org/10.3389/fctls.2024.1353746","url":null,"abstract":"In recent years, the electrochemical synthesis of peroxides has attracted renewed interest as a potential environmentally friendly production compared to the established anthraquinone process. In addition, it is possible to produce the peroxides directly on site, eliminating the need for expensive and hazardous transportation and storage. Cathodic production of hydrogen peroxide from oxygen is already quite well developed. Anodic production from water, on the other hand, is still facing significant challenges, despite its historic pioneering role. In this manuscript we show that anodic and cathodic synthesis of peroxides can even be combined to achieve greater than 100% current efficiency (CE) due to the combined effect of both half-reactions. So far, similar devices have always employed different electrolytes for each, which necessitated the use of a membrane and posed contamination risk. However, herein we show that both half-reactions can also employ the same electrolyte. This enables even an undivided cell, omitting the need for the expensive membranes. Despite its simplicity, this setup yielded an outstanding performance with a combined CE of 144%.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"2 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140963576","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}
Pub Date : 2024-02-16DOI: 10.3389/fctls.2024.1360702
Androniki Spanou, Alexandra Moschona, Eleni Theodosiou, S. Patsios, Ioannis V. Pavlidis
Biodiesel is synthesized by the transesterification of triglycerides of oils with short-chain alcohols, such as methanol and ethanol. According to the Renewable Energy Directive guidelines (RED II 2018/2001/EU) the contribution of advanced biofuels, which do not include edible oils, towards the overall EU target, is at 1% in 2025 and at least 3.5% in 2030. Bioprocesses that valorize non-edible oils for the production of second-generation biodiesel could play a critical role in achieving this goal. Immobilized lipases, as well as other enzyme classes, such as cutinases and acyltransferases, are utilized as biocatalysts for this process. For the sustainability of the process, renewable materials can be used as immobilization matrices, or even enzymes anchored on the cells as whole-cell biocatalysts. Membrane reactors can also be employed to facilitate the enzymatic transesterification by conducting a continuous enzymatic reaction and simultaneously separate the products in a single operation. The advances on the aforementioned fast-pacing fields are presented in this work.
生物柴油是通过油类甘油三酯与甲醇和乙醇等短链醇的酯交换反应合成的。根据可再生能源指令指南（RED II 2018/2001/EU），高级生物燃料（不包括食用油）对欧盟总体目标的贡献率在 2025 年为 1%，2030 年至少为 3.5%。为生产第二代生物柴油而对非食用油进行估值的生物工艺可在实现这一目标方面发挥关键作用。固定化脂肪酶以及其他酶类（如角质酶和酰基转移酶）可用作该工艺的生物催化剂。为保证工艺的可持续性，可使用可再生材料作为固定基质，甚至将酶固定在细胞上作为全细胞生物催化剂。膜反应器也可用于促进酶促酯交换反应，在一次操作中进行连续的酶促反应并同时分离产物。本文介绍了上述快速发展领域的进展。
{"title":"Novel concepts for the biocatalytic synthesis of second-generation biodiesel","authors":"Androniki Spanou, Alexandra Moschona, Eleni Theodosiou, S. Patsios, Ioannis V. Pavlidis","doi":"10.3389/fctls.2024.1360702","DOIUrl":"https://doi.org/10.3389/fctls.2024.1360702","url":null,"abstract":"Biodiesel is synthesized by the transesterification of triglycerides of oils with short-chain alcohols, such as methanol and ethanol. According to the Renewable Energy Directive guidelines (RED II 2018/2001/EU) the contribution of advanced biofuels, which do not include edible oils, towards the overall EU target, is at 1% in 2025 and at least 3.5% in 2030. Bioprocesses that valorize non-edible oils for the production of second-generation biodiesel could play a critical role in achieving this goal. Immobilized lipases, as well as other enzyme classes, such as cutinases and acyltransferases, are utilized as biocatalysts for this process. For the sustainability of the process, renewable materials can be used as immobilization matrices, or even enzymes anchored on the cells as whole-cell biocatalysts. Membrane reactors can also be employed to facilitate the enzymatic transesterification by conducting a continuous enzymatic reaction and simultaneously separate the products in a single operation. The advances on the aforementioned fast-pacing fields are presented in this work.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139960899","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}
Pub Date : 2024-02-08DOI: 10.3389/fctls.2024.1323322
Christin M. Hamm, Selina Schneider, Stefanie Hild, R. Neuber, Thorsten Matthée, Jens Krümberg, M. Stöckl, Klaus-Michael Mangold, Jürgen Kintrup
The generation of “green” oxidizing agents by electrochemical synthesis opens the field for sustainable, on-demand, and on-site production, which is often based on non-critical starting materials. In this study, electrosyntheses were carried out on different cathode and anode materials. In half-cell experiments, the cathodic synthesis of peracetic acid (PAA) was investigated on gas diffusion electrodes (GDEs), reaching 22.6 mmol L−1 of PAA with a current efficiency (CE) of 7.4%. Moreover, peroxodicarbonate (PODIC®) was produced anodically on boron-doped diamond (BDD) electrodes with concentrations as high as 42.7 mmol L−1 PODIC® and a CE of 30.3%. Both cathodic and anodic processes were individually examined and improved. Finally, the half-cell reactions were combined as a proof of concept in a parallel paired electrolysis cell for the first time to achieve an increased overall CE.
{"title":"Parallel paired electrolysis of green oxidizing agents by the combination of a gas diffusion cathode and boron-doped diamond anode","authors":"Christin M. Hamm, Selina Schneider, Stefanie Hild, R. Neuber, Thorsten Matthée, Jens Krümberg, M. Stöckl, Klaus-Michael Mangold, Jürgen Kintrup","doi":"10.3389/fctls.2024.1323322","DOIUrl":"https://doi.org/10.3389/fctls.2024.1323322","url":null,"abstract":"The generation of “green” oxidizing agents by electrochemical synthesis opens the field for sustainable, on-demand, and on-site production, which is often based on non-critical starting materials. In this study, electrosyntheses were carried out on different cathode and anode materials. In half-cell experiments, the cathodic synthesis of peracetic acid (PAA) was investigated on gas diffusion electrodes (GDEs), reaching 22.6 mmol L−1 of PAA with a current efficiency (CE) of 7.4%. Moreover, peroxodicarbonate (PODIC®) was produced anodically on boron-doped diamond (BDD) electrodes with concentrations as high as 42.7 mmol L−1 PODIC® and a CE of 30.3%. Both cathodic and anodic processes were individually examined and improved. Finally, the half-cell reactions were combined as a proof of concept in a parallel paired electrolysis cell for the first time to achieve an increased overall CE.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139791536","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}
Pub Date : 2024-02-08DOI: 10.3389/fctls.2024.1323322
Christin M. Hamm, Selina Schneider, Stefanie Hild, R. Neuber, Thorsten Matthée, Jens Krümberg, M. Stöckl, Klaus-Michael Mangold, Jürgen Kintrup
The generation of “green” oxidizing agents by electrochemical synthesis opens the field for sustainable, on-demand, and on-site production, which is often based on non-critical starting materials. In this study, electrosyntheses were carried out on different cathode and anode materials. In half-cell experiments, the cathodic synthesis of peracetic acid (PAA) was investigated on gas diffusion electrodes (GDEs), reaching 22.6 mmol L−1 of PAA with a current efficiency (CE) of 7.4%. Moreover, peroxodicarbonate (PODIC®) was produced anodically on boron-doped diamond (BDD) electrodes with concentrations as high as 42.7 mmol L−1 PODIC® and a CE of 30.3%. Both cathodic and anodic processes were individually examined and improved. Finally, the half-cell reactions were combined as a proof of concept in a parallel paired electrolysis cell for the first time to achieve an increased overall CE.
{"title":"Parallel paired electrolysis of green oxidizing agents by the combination of a gas diffusion cathode and boron-doped diamond anode","authors":"Christin M. Hamm, Selina Schneider, Stefanie Hild, R. Neuber, Thorsten Matthée, Jens Krümberg, M. Stöckl, Klaus-Michael Mangold, Jürgen Kintrup","doi":"10.3389/fctls.2024.1323322","DOIUrl":"https://doi.org/10.3389/fctls.2024.1323322","url":null,"abstract":"The generation of “green” oxidizing agents by electrochemical synthesis opens the field for sustainable, on-demand, and on-site production, which is often based on non-critical starting materials. In this study, electrosyntheses were carried out on different cathode and anode materials. In half-cell experiments, the cathodic synthesis of peracetic acid (PAA) was investigated on gas diffusion electrodes (GDEs), reaching 22.6 mmol L−1 of PAA with a current efficiency (CE) of 7.4%. Moreover, peroxodicarbonate (PODIC®) was produced anodically on boron-doped diamond (BDD) electrodes with concentrations as high as 42.7 mmol L−1 PODIC® and a CE of 30.3%. Both cathodic and anodic processes were individually examined and improved. Finally, the half-cell reactions were combined as a proof of concept in a parallel paired electrolysis cell for the first time to achieve an increased overall CE.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"67 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139851272","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}
Pub Date : 2024-01-31DOI: 10.3389/fctls.2023.1285074
P. Quaedflieg, Lisanne M. H. Jente, Monika Müller, Linda Vermote, Victor Plesciuc, Jan-Metske van der Laan, Lone Nielsen, Martin Schürmann
We here report four biocatalytic approaches for the synthesis of the protected amino acid building block α-benzyl L-glutamate. Screenings of these routes to identify active and selective enzymes were conducted, and major hits were confirmed in retest reactions. In the first approach, N-Boc L-glutamic acid is mono-benzylesterified by the protease Alcalase with 81% yield; and in the other three approaches, a biocatalytic γ-selective hydrolysis of α,γ-dibenzyl L-glutamate, a selective amide hydrolysis of α-benzyl L-glutamine, and a selective lactam hydrolysis of alpha-benzyl L-pyroglutamate is performed with up to 71% yield.
{"title":"Biocatalytic route scouting and enzyme screening toward the synthesis of α-benzyl L-glutamate","authors":"P. Quaedflieg, Lisanne M. H. Jente, Monika Müller, Linda Vermote, Victor Plesciuc, Jan-Metske van der Laan, Lone Nielsen, Martin Schürmann","doi":"10.3389/fctls.2023.1285074","DOIUrl":"https://doi.org/10.3389/fctls.2023.1285074","url":null,"abstract":"We here report four biocatalytic approaches for the synthesis of the protected amino acid building block α-benzyl L-glutamate. Screenings of these routes to identify active and selective enzymes were conducted, and major hits were confirmed in retest reactions. In the first approach, N-Boc L-glutamic acid is mono-benzylesterified by the protease Alcalase with 81% yield; and in the other three approaches, a biocatalytic γ-selective hydrolysis of α,γ-dibenzyl L-glutamate, a selective amide hydrolysis of α-benzyl L-glutamine, and a selective lactam hydrolysis of alpha-benzyl L-pyroglutamate is performed with up to 71% yield.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"34 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140479316","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}
Pub Date : 2024-01-29DOI: 10.3389/fctls.2023.1359527
Pablo Domínguez de María
{"title":"Grand challenges in industrial catalysis: let´s put academia and industry on the same page!","authors":"Pablo Domínguez de María","doi":"10.3389/fctls.2023.1359527","DOIUrl":"https://doi.org/10.3389/fctls.2023.1359527","url":null,"abstract":"","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"69 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140486509","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}
Pub Date : 2024-01-24DOI: 10.3389/fctls.2023.1275281
Sarah P. Black, Melinda Liu, Cesar Castillo, Wynne Coradeli, Filbert Totsingan, C. Edson, Sagar D. Khare, Richard A. Gross
Introduction: Glycopeptides contain carbohydrate moieties (glycans) covalently attached to the side chain and/or terminal peptide units. Since glycans are present on cell surfaces, these constructs can potentially address a wide array of therapeutic functions. To overcome the deficiencies associated with current synthetic routes to glycopeptides, such as costly processes and toxic reagents, this work aimed to develop versatile environmentally friendly protease-catalyzed peptide synthesis routes to peptides decorated with a glycan at their N-terminus.Methods: “Grafters” were first synthesized that consist of a glycan conjugated directly, or through a spacer, to the amine group of L-Phe-ethyl ester (Phe-OEt). The role of Phe-OEt is to increase the conjugate’s recognition by the protease (papain) catalytic active site. A series of grafters were synthesized with variation of the glycan structure, linkage-chemistry, and presence of an oligo (ethylene glycol) “spacer” of varied length between the glycan and Phe-OEt moiety. High grafter efficiency will result by the successful acceptance of the grafter at the enzymes S1/S2 subsites, formation of an acyl enzyme complex and subsequent conversion to glycan-terminated oligo(Leu)x (x ≥ 1), as opposed to construction of non-glycan N-terminated oligo(Leu)x.Results and discussion: While glycan-Phe-OEt grafters without a spacer between the glycan and Phe-OEt resulted in low grafter efficiency (8.3% ± 2.0%), insertion of a short oligo (ethylene glycol) spacer between the glycan and Phe-OEt moieties (glycan-PEGn-Phe-OEt, n ≥ 3) increased the grafter efficiency by 3-fold–24.5% ± 1.8%. In addition, computational modeling was performed using Rosetta software provided insights on a molecular level of how grafter efficiency is influenced by the PEG spacer length.
{"title":"The chemoenzymatic synthesis of glycan-terminated oligo(Leu)x","authors":"Sarah P. Black, Melinda Liu, Cesar Castillo, Wynne Coradeli, Filbert Totsingan, C. Edson, Sagar D. Khare, Richard A. Gross","doi":"10.3389/fctls.2023.1275281","DOIUrl":"https://doi.org/10.3389/fctls.2023.1275281","url":null,"abstract":"Introduction: Glycopeptides contain carbohydrate moieties (glycans) covalently attached to the side chain and/or terminal peptide units. Since glycans are present on cell surfaces, these constructs can potentially address a wide array of therapeutic functions. To overcome the deficiencies associated with current synthetic routes to glycopeptides, such as costly processes and toxic reagents, this work aimed to develop versatile environmentally friendly protease-catalyzed peptide synthesis routes to peptides decorated with a glycan at their N-terminus.Methods: “Grafters” were first synthesized that consist of a glycan conjugated directly, or through a spacer, to the amine group of L-Phe-ethyl ester (Phe-OEt). The role of Phe-OEt is to increase the conjugate’s recognition by the protease (papain) catalytic active site. A series of grafters were synthesized with variation of the glycan structure, linkage-chemistry, and presence of an oligo (ethylene glycol) “spacer” of varied length between the glycan and Phe-OEt moiety. High grafter efficiency will result by the successful acceptance of the grafter at the enzymes S1/S2 subsites, formation of an acyl enzyme complex and subsequent conversion to glycan-terminated oligo(Leu)x (x ≥ 1), as opposed to construction of non-glycan N-terminated oligo(Leu)x.Results and discussion: While glycan-Phe-OEt grafters without a spacer between the glycan and Phe-OEt resulted in low grafter efficiency (8.3% ± 2.0%), insertion of a short oligo (ethylene glycol) spacer between the glycan and Phe-OEt moieties (glycan-PEGn-Phe-OEt, n ≥ 3) increased the grafter efficiency by 3-fold–24.5% ± 1.8%. In addition, computational modeling was performed using Rosetta software provided insights on a molecular level of how grafter efficiency is influenced by the PEG spacer length.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"13 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139602671","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}
Pub Date : 2023-07-26DOI: 10.3389/fctls.2023.1231765
Jan Gebauer, J. Pietruszka, T. Classen
Introduction: The antimicrobial pyrrolnitrin from Pseudomonas strains is formed in four steps from tryptophan and comprises two flavin-dependent halogenases. Both PrnC and PrnA can carry out regioselective chlorination and bromination and are carrier protein-independent. Whilst the tryptophan halogenase PrnA has been studied in detail in the past, this study focuses on the pyrrole halogenating enzyme PrnC.Methods: The halogenating enzyme PrnC, as well as the essential electron suppliers, the flavin reductases, have been produced soluble in E. coli. Furthermore, a screening of a rational compound library revealed that the pyrrole is essential for substrate recognition; however, the substitution pattern of the benzene ring is not limiting the catalysis.Results and discussion: This renders PrnC to be a synthetically valuable enzyme for the synthesis of pyrrolnitrin congeners. For its natural substrate monodechloroaminopyrrolnitrin (MDA), the KM value was determined as 14.4 ± 1.2 µM and a kcat of 1.66 ± 0.02 min−1, which is comparable to other halogenases.
{"title":"Expression and characterization of PrnC—a flavin-dependent halogenase from the pyrrolnitrin biosynthetic pathway of Pseudomonas protegens Pf-5","authors":"Jan Gebauer, J. Pietruszka, T. Classen","doi":"10.3389/fctls.2023.1231765","DOIUrl":"https://doi.org/10.3389/fctls.2023.1231765","url":null,"abstract":"Introduction: The antimicrobial pyrrolnitrin from Pseudomonas strains is formed in four steps from tryptophan and comprises two flavin-dependent halogenases. Both PrnC and PrnA can carry out regioselective chlorination and bromination and are carrier protein-independent. Whilst the tryptophan halogenase PrnA has been studied in detail in the past, this study focuses on the pyrrole halogenating enzyme PrnC.Methods: The halogenating enzyme PrnC, as well as the essential electron suppliers, the flavin reductases, have been produced soluble in E. coli. Furthermore, a screening of a rational compound library revealed that the pyrrole is essential for substrate recognition; however, the substitution pattern of the benzene ring is not limiting the catalysis.Results and discussion: This renders PrnC to be a synthetically valuable enzyme for the synthesis of pyrrolnitrin congeners. For its natural substrate monodechloroaminopyrrolnitrin (MDA), the KM value was determined as 14.4 ± 1.2 µM and a kcat of 1.66 ± 0.02 min−1, which is comparable to other halogenases.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44884471","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}
Pub Date : 2023-07-05DOI: 10.3389/fctls.2023.1213803
Lucas Spiske, P. Plessow, K. Kazmierczak, Bart D. Vandegehuchte, F. Studt
Hybrid density functional theory calculations are used to investigate different mechanisms of the isomerization of n-butane to isobutane via intermediate formation of olefins. The monomolecular mechanism for isomerization of butene and isobutene is found to be prevalent, with a Gibbs free energy barrier of 155 kJ/mol at 400°C, compared to the bimolecular mechanism (190 kJ/mol) due to less favorable entropy for the latter. Hydrogen transfer reactions that convert olefins into alkanes (and vice versa) are also included in the investigations, and show a free energy barrier of 203 kJ/mol for conversion of isobutene to isobutane. Additionally, a methyl transfer mechanism is discussed as a possible pathway for formation of C3 and C5 side products, in comparison to the bimolecular mechanism; the highest barrier of the initial methyl transfer is calculated to be 227 kJ/mol. We discuss the influence of entropy and anharmonicity on all mechanisms, stating that through the uncertainties in computational methods when calculating these systems, the calculated reaction barriers are likely to be overestimated here.
{"title":"Theoretical investigation of catalytic n-butane isomerization over H-SSZ-13","authors":"Lucas Spiske, P. Plessow, K. Kazmierczak, Bart D. Vandegehuchte, F. Studt","doi":"10.3389/fctls.2023.1213803","DOIUrl":"https://doi.org/10.3389/fctls.2023.1213803","url":null,"abstract":"Hybrid density functional theory calculations are used to investigate different mechanisms of the isomerization of n-butane to isobutane via intermediate formation of olefins. The monomolecular mechanism for isomerization of butene and isobutene is found to be prevalent, with a Gibbs free energy barrier of 155 kJ/mol at 400°C, compared to the bimolecular mechanism (190 kJ/mol) due to less favorable entropy for the latter. Hydrogen transfer reactions that convert olefins into alkanes (and vice versa) are also included in the investigations, and show a free energy barrier of 203 kJ/mol for conversion of isobutene to isobutane. Additionally, a methyl transfer mechanism is discussed as a possible pathway for formation of C3 and C5 side products, in comparison to the bimolecular mechanism; the highest barrier of the initial methyl transfer is calculated to be 227 kJ/mol. We discuss the influence of entropy and anharmonicity on all mechanisms, stating that through the uncertainties in computational methods when calculating these systems, the calculated reaction barriers are likely to be overestimated here.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44286257","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}
Pub Date : 2023-06-16DOI: 10.3389/fctls.2023.1184959
Y. Ho, T. Izoré, J. Kaczmarski, Edward Marschall, M. S. Ratnayake, J. Tailhades, D. Steer, R. Schittenhelm, M. Tosin, C. Jackson, M. Cryle
In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering.
{"title":"Exploring the selectivity and engineering potential of an NRPS condensation domain involved in the biosynthesis of the thermophilic siderophore fuscachelin","authors":"Y. Ho, T. Izoré, J. Kaczmarski, Edward Marschall, M. S. Ratnayake, J. Tailhades, D. Steer, R. Schittenhelm, M. Tosin, C. Jackson, M. Cryle","doi":"10.3389/fctls.2023.1184959","DOIUrl":"https://doi.org/10.3389/fctls.2023.1184959","url":null,"abstract":"In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41758794","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}
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