Background: Ethylene is one of the most used chemical monomers derived from non-renewable sources and we are investigating the possibility of producing it in yeast via the ethylene forming enzyme (EFE) from Pseudomonas syringae. To enable engineering strategies to improve the enzyme, it is necessary to identify the regions and amino acid residues involved in ethylene formation.
Results: We identified the open reading frame for the EFE homolog in Penicillium digitatum and also showed its capability of mediating ethylene production in yeast. The sequence of the EFE homologs from P.digitatum and P. syringae was compared to that of the non-functional EFE-homolog from Penicillium chrysogenum and ten amino acids were found to correlate with ethylene production. Several of these amino acid residues were found to be important for ethylene production via point mutations in P. syringae EFE. The EFE homolog from P. chrysogenum was engineered at 10 amino acid residues to mimic the P. syringae EFE, but this did not confer ethylene producing capability.Furthermore, we predicted the structure of EFE by homology to known structures of 2-oxoglutarate/Fe(II) dependent dioxygenases. Three of the amino acids correlating with ethylene production are located in the predicted 2-oxoglutarate binding domain. A protein domain specific for the EFE-class was shown to be essential for activity. Based on the structure and alanine substitutions, it is likely that amino acids (H189, D191 and H268) are responsible for binding the Fe(II) ligand.
Conclusion: We provide further insight into the structure and function of the ethylene forming (EFE) - subclass of 2-oxoglutarate/Fe(II) dependent dioxygenases. We conclude that residues in addition to the 10 identified positions implicated in ethylene production by sequence comparison, are important for determining ethylene formation. We also demonstrate the use of an alternative EFE gene. The data from this study will provide the basis for directed protein engineering to enhance the ethylene production capability and properties of EFE.
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http://dx.doi.org/10.1186/1471-2091-15-22 | DOI Listing |
ACS Catal
January 2025
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Partial oxidation of ethylene over silver catalysts produces more than 30 million metric tons of ethylene oxide (EO) annually. However, the form of active silver surfaces, reactive oxygen species, and dominant pathways of this chemical reaction remains controversial despite decades of research. Here, we use Raman spectroscopy and transient kinetic measurements to demonstrate that higher coverages of peroxide species, present only upon Ag oxide surfaces that form , correlate with greater selectivities to EO.
View Article and Find Full Text PDFInorg Chem
January 2025
School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
The ability to finely tune the nuclearity of active metal sites is critical for designing highly selective catalysts, especially for hydrogenation processes. In this work, we developed a novel PdCu catalyst with an ordered body-centered cubic (BCC) structure, enabling precise control over Pd nuclearity to optimize selectivity. Using a facile polyol synthesis method, we modulated the Pd coordination environment, reducing the Pd-Pd coordination number from 3 (disordered face-centered cubic, FCC) to 0 (ordered BCC), thereby achieving full isolation of Pd by the surrounding Cu atoms.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Anhui Laboratory of Molecule-Based Materials, Key Laboratory of Functional Molecular Solids, Ministry of Education, School of Chemistry and Materials Science, Anhui Normal University, Wuhu 241002, China.
The production of high molecular weight polyethylene particles in aqueous environments has received considerable attention, yet reports on the formation of polyethylene oil within water remain scarce. Herein, we present findings that demonstrate the oligomerization of ethylene by certain iminopyridyl Pd(II) catalysts in water, resulting in the synthesis of hyperbranched ethylene oligomers. It is worth highlighting the intriguing observation that these catalysts exhibited a remarkable catalytic longevity in aqueous medium and ultimately facilitated the generation of a substantial liquid polyolefin phase from water.
View Article and Find Full Text PDFSmall
January 2025
Key Laboratory of Marine Chemistry Theory and Technology (Ministry of Education), College of Chemistry & Chemical Engineering, Ocean University of China, 238 Songling Road, Qingdao, 266100, China.
Achieving fast conversion and precise regulation of product selectivity in electrochemical CO reduction reaction (CORR) remains a challenge. The space confinement effect provides a theoretical basis for the design of catalysts of different morphology and sizes and reveals the physical phenomena caused by the confinement of electrons and other particles at the nanoscale. In this work, a semi-confinement concept is introduced and a mesoporous silica nanosphere supported Cu catalyst (Cu-MSN) is prepared as a typical example to realize CORR enhancement and product selectivity regulation (methane vs ethylene).
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
School of Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160 Pearse St., Dublin 2, Ireland.
Novel ionic liquid catalysts comprising terephthalate anions are capable of promoting the neutral hydrolysis of relatively large flake sizes of poly(ethylene terephthalate) at 0.5 mol% loading (200 °C, 4 h, 94% yield) without either attendant product inhibition or product contamination by protonated catalyst. Catalysts with large, lipophilic phosphonium cations outperform more polar variants.
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