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Hafiz Saqib Ali Dr. Richard H. Henchman Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):13093-13102
A recently characterized cytochrome P450 isozyme GcoA activates lignin components through a selective O-demethylation or alternatively an acetal formation reaction. These are important reactions in biotechnology and, because lignin is readily available; it being the main component in plant cell walls. In this work we present a density functional theory study on a large active site model of GcoA to investigate syringol activation by an iron(IV)-oxo heme cation radical oxidant (Compound I) leading to hemiacetal and acetal products. Several substrate-binding positions were tested and full energy landscapes calculated. The study shows that substrate positioning determines the product distributions. Thus, with the phenol group pointing away from the heme, an O-demethylation is predicted, whereas an initial hydrogen-atom abstraction of the weak phenolic O-H group would trigger a pathway leading to ring-closure to form acetal products. Predictions on how to engineer P450 GcoA to get more selective product distributions are given. 相似文献
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Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5308-5327
Mononuclear iron-containing enzymes are highly versatile oxidants that often react stereospecifically and/or regioselectively with substrates. Combined experimental and computational studies on heme monooxygenases, nonheme iron dioxygenases and halogenases have revealed the intricate details of the second-coordination sphere, which determine this specificity and selectivity. These second-coordination sphere effects originate from the positioning of the substrate and oxidant, which involve the binding of the co-factors and substrate into the active site of the protein. In addition, some enzymes affect the selectivity and reactivity through charge-stabilization from nearby bound cations/anions, an induced electric field or through the positioning of salt bridges and hydrogen-bonding interactions to first-coordination sphere iron ligands and/or the substrate. Examples of all of these second-coordination sphere effects in iron-containing enzymes and how these influence structure and reactivity are given. 相似文献
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Stephanie M. Delgado Sam C. P. Norris Andrea M. Kasko 《Journal of polymer science. Part A, Polymer chemistry》2022,60(5):825-841
Hydrogels are attractive materials for generating 4D shapes due to their ability to undergo pronounced volume changes in response to several stimuli, including light. We previously reported shape-changing hydrogels actuated by long-wave UV and visible light in the presence of live cells using poly(ethylene glycol) macromers incorporating different photodegradable ortho-nitrobenzyl (o-NB) groups. In this comprehensive study, we determine the effect of chemical structure of different o-NB macromers (which influences molar absorptivity and rate constant of degradation), composition (macromer weight percent), fabrication design (initial gel thickness) and environment (ionic strength of solution) on light-induced hydrogel folding. We demonstrate successful photopolymerization and subsequent photodegradation of hydrogels, multistep folding, and live-cell encapsulation. This hydrogel system may be useful as new tool in stem cell differentiation and developmental biology research, facilitating the in vitro investigation of processes that are sensitive to both physical and temporal stimuli. 相似文献
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Matthew A. Bedics Hayleigh Kearns Jordan M. Cox Sam Mabbott Fatima Ali Neil C. Shand Karen Faulds Jason B. Benedict Duncan Graham Michael R. Detty 《Chemical science》2015,6(4):2302-2306
Surfaced enhanced Raman scattering (SERS) nanotags operating with 1280 nm excitation were constructed from reporter molecules selected from a library of 14 chalcogenopyrylium dyes containing phenyl, 2-thienyl, and 2-selenophenyl substituents and a surface of hollow gold nanoshells (HGNs). These 1280 SERS nanotags are unique as they have multiple chalcogen atoms available which allow them to adsorb strongly onto the gold surface of the HGN thus producing exceptional SERS signals at this long excitation wavelength. Picomolar limits of detection (LOD) were observed and individual reporters of the library were identified by principal component analysis and classified according to their unique structure and SERS spectra. 相似文献
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Ehsan Bahmani Babak Faraji Dizaji Sam Talaei Shahnaz Koushkbaghi Hamid Yazdani Parvaneh Ghaderi-shekhi Abadi Mohammad Akrami Mohsen Shahrousvand Fariborz Sharifian Jazi Mohammad Irani 《先进技术聚合物》2023,34(2):789-799
In the present study, paclitaxel (PTX), multi-walled carbon nanotubes (MWCNTs), and doxorubicin (DOX) have been simultaneously doped into the poly(ϵ-caprolactone) (PCL)/chitosan/zein core-shell nanofibers to increase its cytotoxicity for MCF-7 breast cancers killing. The physico-chemical properties of synthesized nanofibers were determined by scanning electron microscope, Fourier-transform infrared spectroscopy, tensile strength, and degradation rate determinations. The in vitro release studies demonstrated the sustained release of drugs from core-shell nanofibrous scaffold. The cytotoxicity and compatibility of core-shell nanofibers were investigated by their treating with MCF-7 breast cancer cells and L929 normal cells, respectively. PCL/PTX/chitosan/zein/MWCNTs/DOX core-shell nanofibers containing 1 wt% MWCNTs, 100 μg ml−1 DOX and 100 μg ml−1 PTX had a high biocompatibility with a 84% MCF-7 cancer cells killing. The in vivo studies revealed the synergic effects of MWCNTs and anticancer drugs on the tumor inhibition. This method could be considered as a new way for developing of MWCNTs loaded-nanofibers for cancer treatment in future. 相似文献
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Thomas Sephton Anastasios Charitou Dr. Cristina Trujillo Dr. Jonathan M. Large Dr. Sam Butterworth Prof. Michael F. Greaney 《Angewandte Chemie (International ed. in English)》2023,62(49):e202310583
Anilines are potentially high-value arylating agents, but are limited by the low reactivity of the strong C−N bond. We show that the reactive intermediate benzyne can be used to both activate anilines, and set-up an aryl transfer reaction in a single step. The reaction does not require any transition metal catalysts or stoichiometric organometallics, and establishes a metal-free route to valuable biaryl products by functionalizing the aniline C−N bond. 相似文献
10.
Young Her Tae-Kyeong Lee Ji Hyeon Ahn Soon Sung Lim Beom-Goo Kang Jung-Seok Park Bora Kim Hyejin Sim Jae-Chul Lee Hyun Sook Kim Tae Heung Sim Hyun Sam Lee Moo-Ho Won 《Molecules (Basel, Switzerland)》2021,26(1)
Since ancient times, various herbs have been used in Asia, including Korea, China, and Japan, for wound healing and antiaging of the skin. In this study, we manufactured and chemically analyzed a novel distillate obtained from a fermented mixture of nine anti-inflammatory herbs (Angelica gigas, Lonicera japonica, Dictamnus dasycarpus Turcz., D. opposita Thunb., Ulmus davidiana var. japonica, Hordeum vulgare var. hexastichon Aschers., Xanthium strumarium L., Cnidium officinale, and Houttuynia cordata Thunb.). The fermentation of natural plants possesses beneficial effects in living systems. These activities are attributed to the chemical conversion of the parent plants to functional constituents which show more potent biological activities. In our current study, the distillate has been manufactured after fermenting the nine oriental medical plants with Lactobacillus fermentum, followed by distilling. We analyzed the chemical ingredients involved in the distillate and evaluated the effects of topical application of the distillate on ultraviolet B (UVB)-induced skin damage in Institute of Cancer Research (ICR) mice. Topical application of the distillate significantly ameliorated the macroscopic and microscopic morphology of the dorsal skin against photodamage induced by UVB radiation. Additionally, our current results showed that topical application of the distillate alleviated collagen disruption and reduced levels of proinflammatory cytokines (tumor necrosis factor alpha and interleukin 1 β expressions) in the dorsal skin against UVB radiation. Taken together, our current findings suggest that the distillate has a potential to be used as a material to develop a photoprotective adjuvant. 相似文献