scholarly journals Identifying the Catalytic Active Site for Propylene Metathesis by Supported ReOx Catalysts

ACS Catalysis ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1962-1976
Author(s):  
Bin Zhang ◽  
Israel E. Wachs
Keyword(s):  
Active Site ◽  
Catalytic Active Site ◽  
Propylene Metathesis

scholarly journals Kinetic studies and homology modeling of a dual-substrate linalool/nerolidol synthase from Plectranthus amboinicus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nur Suhanawati Ashaari ◽  
Mohd Hairul Ab. Rahim ◽  
Suriana Sabri ◽  
Kok Song Lai ◽  
Adelene Ai-Lian Song ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Efficiency ◽  
Kinetic Studies ◽  
Homology Model ◽  
Biochemical Properties ◽  
Terpene Synthase ◽  
Monoterpene Synthase ◽  
Terminal Domain ◽  
Catalytic Active Site ◽  
Plectranthus Amboinicus

AbstractLinalool and nerolidol are terpene alcohols that occur naturally in many aromatic plants and are commonly used in food and cosmetic industries as flavors and fragrances. In plants, linalool and nerolidol are biosynthesized as a result of respective linalool synthase and nerolidol synthase, or a single linalool/nerolidol synthase. In our previous work, we have isolated a linalool/nerolidol synthase (designated as PamTps1) from a local herbal plant, Plectranthus amboinicus, and successfully demonstrated the production of linalool and nerolidol in an Escherichia coli system. In this work, the biochemical properties of PamTps1 were analyzed, and its 3D homology model with the docking positions of its substrates, geranyl pyrophosphate (C10) and farnesyl pyrophosphate (C15) in the active site were constructed. PamTps1 exhibited the highest enzymatic activity at an optimal pH and temperature of 6.5 and 30 °C, respectively, and in the presence of 20 mM magnesium as a cofactor. The Michaelis–Menten constant (Km) and catalytic efficiency (kcat/Km) values of 16.72 ± 1.32 µM and 9.57 × 10–3 µM−1 s−1, respectively, showed that PamTps1 had a higher binding affinity and specificity for GPP instead of FPP as expected for a monoterpene synthase. The PamTps1 exhibits feature of a class I terpene synthase fold that made up of α-helices architecture with N-terminal domain and catalytic C-terminal domain. Nine aromatic residues (W268, Y272, Y299, F371, Y378, Y379, F447, Y517 and Y523) outlined the hydrophobic walls of the active site cavity, whilst residues from the RRx8W motif, RxR motif, H-α1 and J-K loops formed the active site lid that shielded the highly reactive carbocationic intermediates from the solvents. The dual substrates use by PamTps1 was hypothesized to be possible due to the architecture and residues lining the catalytic site that can accommodate larger substrate (FPP) as demonstrated by the protein modelling and docking analysis. This model serves as a first glimpse into the structural insights of the PamTps1 catalytic active site as a multi-substrate linalool/nerolidol synthase.

scholarly journals The Geometry of the Catalytic Active Site in [FeFe]-Hydrogenases is Determined by Hydrogen Bonding and Proton Transfer

2019 ◽  
Author(s):  
Jifu Duan ◽  
Stefan Mebs ◽  
Moritz Senger ◽  
Konstantin Laun ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Active Site ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Catalytic Active Site ◽  
Catalytic Intermediates ◽  
Time Resolved Infrared Spectroscopy

The H2 conversion and CO inhibition reactivity of nine [FeFe]-hydrogenase constructs with semi-artificial cofactors was studied by in situ and time-resolved infrared spectroscopy, X-ray crystallography, and theoretical methods. Impaired hydrogen turnover and proton transfer as well as characteristic CO inhibition/ reactivation kinetics are assigned to varying degrees of hydrogen-bonding interactions at the active site. We show that the probability to adopt catalytic intermediates is modulated by intramolecular and protein-cofactor interactions that govern structural dynamics at the active site of [FeFe]-hydrogenases.<br>

scholarly journals The Geometry of the Catalytic Active Site in [FeFe]-Hydrogenases is Determined by Hydrogen Bonding and Proton Transfer

2019 ◽  
Author(s):  
Jifu Duan ◽  
Stefan Mebs ◽  
Moritz Senger ◽  
Konstantin Laun ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Active Site ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Catalytic Active Site ◽  
Catalytic Intermediates ◽  
Time Resolved Infrared Spectroscopy

The H2 conversion and CO inhibition reactivity of nine [FeFe]-hydrogenase constructs with semi-artificial cofactors was studied by in situ and time-resolved infrared spectroscopy, X-ray crystallography, and theoretical methods. Impaired hydrogen turnover and proton transfer as well as characteristic CO inhibition/ reactivation kinetics are assigned to varying degrees of hydrogen-bonding interactions at the active site. We show that the probability to adopt catalytic intermediates is modulated by intramolecular and protein-cofactor interactions that govern structural dynamics at the active site of [FeFe]-hydrogenases.<br>

Mechanical bonding activation in rotaxane-based organocatalysts

2021 ◽  
Author(s):  
Jesus de Maria Perez ◽  
Julio Puigcerver ◽  
Tainára Orlando ◽  
Aurelia Pastor ◽  
Marcos A P Martins ◽  
...  
Keyword(s):  
Secondary Amine ◽  
Active Site ◽  
Catalytic Active Site ◽  
Mechanical Bonding ◽  
Hydrogen Bonded

We report here the enhanced efficiency as organocatalysts of a series of succinamide-based hydrogen-bonded [2]rotaxanes functionalized with an acyclic secondary amine as the catalytic active site. We also evaluated their...

scholarly journals Phenoxyethyl Piperidine/Morpholine Derivatives as PAS and CAS Inhibitors of Cholinesterases: Insights for Future Drug Design

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yaghoub Pourshojaei ◽  
Ardavan Abiri ◽  
Khalil Eskandari ◽  
Zahra Haghighijoo ◽  
Najmeh Edraki ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Active Site ◽  
Inhibitory Activity ◽  
Reference Drug ◽  
Catalytic Active Site ◽  
Electric Eel ◽  
Interesting Candidate ◽  
Future Drug ◽  
Morpholine Derivatives

AbstractAcetylcholinesterase (AChE) catalyzes the conversion of Aβ peptide to its aggregated form and the peripheral anionic site (PAS) of AChE is mainly involved in this phenomenon. Also catalytic active site (CAS) of donepezil stimulates the break-down of acetylcholine (ACh) and depletion of ACh in cholinergic synapses are well established in brains of patients with AD. In this study, a set of compounds bearing phenoxyethyl amines were synthesized and their inhibitory activity toward electric eel AChE (eeAChE) and equine butyrylcholinesterase (eqBuChE) were evaluated. Molecular dynamics (MD) was employed to record the binding interactions of best compounds against human cholinesterases (hAChE and hBuChE) as well as donepezil as reference drug. In vitro results revealed that compound 5c is capable of inhibiting eeAChE activity at IC50 of 0.50 µM while no inhibitory activity was found for eqBuChE for up to 100 µM concentrations. Compound 5c, also due to its facile synthesis, small structure and high selectivity for eeAChE would be very interesting candidate in forthcoming studies. The main interacting parts of compound 5c and compound 7c (most potent eeAChE and eqBuChE inhibitors respectively) with receptors which confer selectivity for AChE and BuChE inhibition were identified, discussed, and compared with donepezil’s interactions. Also during MD simulation it was discovered for the first time that binding of substrates like donepezil to dual CAS and PAS or solely CAS region might have a suppressive impact on 4-α-helical bundles near the tryptophan amphiphilic tetramerization (WAT) domain of AChE and residues which are far away from AChE active site. The results proposed that residues involved in donepezil interactions (Trp86 and Phe295) which are located in CAS and mid-gorge are the mediator of conformational changes in whole protein structure.

A competent catalytic active site is necessary for substrate induced dimer assembly in triosephosphate isomerase

2017 ◽  
Vol 1865 (11) ◽  
pp. 1423-1432 ◽  
Author(s):  
Pedro Jimenez-Sandoval ◽  
Jose Luis Vique-Sanchez ◽  
Marisol López Hidalgo ◽  
Gilberto Velazquez-Juarez ◽  
Corina Diaz-Quezada ◽  
...  
Keyword(s):  
Active Site ◽  
Triosephosphate Isomerase ◽  
Catalytic Active Site

scholarly journals Structural Determinants Responsible for the Preferential Insertion of Ribonucleotides by Bacterial NHEJ PolDom

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 203
Author(s):  
Alejandro Sánchez-Salvador ◽  
Miguel de Vega
Keyword(s):  
Active Site ◽  
Strand Break ◽  
Biochemical Properties ◽  
Nonhomologous End Joining ◽  
Polymerization Reaction ◽  
End Joining ◽  
Structural Determinants ◽  
Intracellular Pool ◽  
Catalytic Active Site

The catalytic active site of the Polymerization Domain (PolDom) of bacterial Ligase D is designed to promote realignments of the primer and template strands and extend mispaired 3′ ends. These features, together with the preferred use of ribonucleotides (NTPs) over deoxynucleotides (dNTPs), allow PolDom to perform efficient double strand break repair by nonhomologous end joining when only a copy of the chromosome is present and the intracellular pool of dNTPs is depleted. Here, we evaluate (i) the role of conserved histidine and serine/threonine residues in NTP insertion, and (ii) the importance in the polymerization reaction of a conserved lysine residue that interacts with the templating nucleotide. To that extent, we have analyzed the biochemical properties of variants at the corresponding His651, Ser768, and Lys606 of Pseudomonas aeruginosa PolDom (Pa-PolDom). The results show that preferential insertion of NMPs is principally due to the histidine that also contributes to the plasticity of the active site to misinsert nucleotides. Additionally, Pa-PolDom Lys606 stabilizes primer dislocations. Finally, we show that the active site of PolDom allows the efficient use of 7,8-dihydro-8-oxo-riboguanosine triphosphate (8oxoGTP) as substrate, a major nucleotide lesion that results from oxidative stress, inserting with the same efficiency both the anti and syn conformations of 8oxoGMP.

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