scholarly journals Subtle Changes in Lipid Environment Have Profound Effects on Membrane Oxidation Chemistry

2018 ◽  
Vol 140 (50) ◽  
pp. 17492-17498 ◽  
Author(s):  
Xinxing Zhang ◽  
Kevin M. Barraza ◽  
Kathleen T. Upton ◽  
J. L. Beauchamp
Keyword(s):  
Membrane Oxidation ◽  
Lipid Environment ◽  
Oxidation Chemistry

Oxidase Catalysis via an Aerobically Generated Dess-Martin Periodinane Analogue

2018 ◽  
Author(s):  
Asim Maity ◽  
Sung-Min Hyun ◽  
Alan Wortman ◽  
David Powers
Keyword(s):  
Chemical Synthesis ◽  
Aerobic Oxidation ◽  
Substrate Oxidation ◽  
Oxidation Catalysis ◽  
Hypervalent Iodine ◽  
Oxidation Reactions ◽  
Broad Array ◽  
Oxidation Chemistry ◽  
Reactive Oxidants

<p>Hypervalent iodine(V) reagents, such as Dess-Martin periodinane (DMP) and 2-iodoxybenzoic acid (IBX), are broadly useful oxidants in chemical synthesis. Development of strategies to access these reagents from O2 would immediately enable use of O2 as a terminal oxidant in a broad array of substrate oxidation reactions. Recently we disclosed the aerobic synthesis of I(III) reagents by intercepting reactive oxidants generated during aldehyde autoxidation. Here, we couple aerobic oxidation of iodobenzenes with disproportionation of the initially generated I(III) compounds to generate I(V) reagents. The aerobically generated I(V) reagents exhibit substrate oxidation chemistry analogous to that of DMP. Further, the developed aerobic generation of I(V) has enabled the first application of I(V) intermediates in aerobic oxidation catalysis.</p>

scholarly journals Co-Translational Insertion of Aquaporins into Liposome for Functional Analysis via an E. coli Based Cell-Free Protein Synthesis System

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1325 ◽  
Author(s):  
Ke Yue ◽  
Tran Nam Trung ◽  
Yiyong Zhu ◽  
Ralf Kaldenhoff ◽  
Lei Kai
Keyword(s):  
Functional Analysis ◽  
Membrane Proteins ◽  
Fluorescent Protein ◽  
Water Channel ◽  
New Approach ◽  
E Coli ◽  
Straightforward Method ◽  
Lipid Environment ◽  
Green Fluorescent ◽  
Eukaryotic Organisms

Aquaporins are important and well-studied water channel membrane proteins. However, being membrane proteins, sample preparation for functional analysis is tedious and time-consuming. In this paper, we report a new approach for the co-translational insertion of two aquaporins from Escherichia coli and Nicotiana tabacum using the CFPS system. This was done in the presence of liposomes with a modified procedure to form homogenous proteo-liposomes suitable for functional analysis of water permeability using stopped-flow spectrophotometry. Two model aquaporins, AqpZ and NtPIP2;1, were successfully incorporated into the liposome in their active forms. Shifted green fluorescent protein was fused to the C-terminal part of AqpZ to monitor its insertion and status in the lipid environment. This new fast approach offers a fast and straightforward method for the functional analysis of aquaporins in both prokaryotic and eukaryotic organisms.

Insights into the Decomposition and Oxidation Chemistry of p-Xylene in Laminar Premixed Flames

2021 ◽  
Vol 125 (15) ◽  
pp. 3189-3197
Author(s):  
Wenhao Yuan ◽  
Long Zhao ◽  
Jiuzhong Yang ◽  
Zhongyue Zhou ◽  
Yuyang Li ◽  
...  
Keyword(s):  
Premixed Flames ◽  
Oxidation Chemistry

scholarly journals The Profound Influence of Lipid Composition on the Catalysis of the Drug Target NADH Type II Oxidoreductase

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 363
Author(s):  
Albert Godoy-Hernandez ◽  
Duncan G. G. McMillan
Keyword(s):  
Acyl Chain ◽  
Cellular Respiration ◽  
Type Ii ◽  
Nadh:Quinone Oxidoreductase ◽  
Chain Composition ◽  
Membrane Bound ◽  
Lipid Environment ◽  
Lipid Specificity ◽  
Mediated Catalysis ◽  
Quinone Pool

Lipids play a pivotal role in cellular respiration, providing the natural environment in which an oxidoreductase interacts with the quinone pool. To date, it is generally accepted that negatively charged lipids play a major role in the activity of quinone oxidoreductases. By changing lipid compositions when assaying a type II NADH:quinone oxidoreductase, we demonstrate that phosphatidylethanolamine has an essential role in substrate binding and catalysis. We also reveal the importance of acyl chain composition, specifically c14:0, on membrane-bound quinone-mediated catalysis. This demonstrates that oxidoreductase lipid specificity is more diverse than originally thought and that the lipid environment plays an important role in the physiological catalysis of membrane-bound oxidoreductases.

scholarly journals Plasticity of Escherichia coli porin channels. Dependence of their conductance on strain and lipid environment.

1991 ◽  
Vol 266 (36) ◽  
pp. 24446-24450
Author(s):  
L.K. Buehler ◽  
S. Kusumoto ◽  
H. Zhang ◽  
J.P. Rosenbusch
Keyword(s):  
Escherichia Coli ◽  
Lipid Environment

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

scholarly journals Studies of transmembrane peptides by pulse dipolar spectroscopy with semi-rigid TOPP spin labels

2021 ◽  
Author(s):  
Igor Tkach ◽  
Ulf Diederichsen ◽  
Marina Bennati
Keyword(s):  
Molecular Level ◽  
Dipolar Interaction ◽  
Spin Labels ◽  
Paramagnetic Centers ◽  
Structural Adaptation ◽  
Paramagnetic Resonance ◽  
Transmembrane Peptides ◽  
Distance Distributions ◽  
Lipid Environment ◽  
Electron Paramagnetic

AbstractElectron paramagnetic resonance (EPR)-based pulsed dipolar spectroscopy measures the dipolar interaction between paramagnetic centers that are separated by distances in the range of about 1.5–10 nm. Its application to transmembrane (TM) peptides in combination with modern spin labelling techniques provides a valuable tool to study peptide-to-lipid interactions at a molecular level, which permits access to key parameters characterizing the structural adaptation of model peptides incorporated in natural membranes. In this mini-review, we summarize our approach for distance and orientation measurements in lipid environment using novel semi-rigid TOPP [4-(3,3,5,5-tetramethyl-2,6-dioxo-4-oxylpiperazin-1-yl)-L-phenylglycine] labels specifically designed for incorporation in TM peptides. TOPP labels can report single peak distance distributions with sub-angstrom resolution, thus offering new capabilities for a variety of TM peptide investigations, such as monitoring of various helix conformations or measuring of tilt angles in membranes. Graphical Abstract

Order-disorder transitions of cytoplasmic N-termini in the mechanisms of P-type ATPases

2020 ◽  
Author(s):  
Khondker Rufaka Hossain ◽  
Daniel Clayton ◽  
Sophia C Goodchild ◽  
Alison Rodger ◽  
Richard James Payne ◽  
...  
Keyword(s):  
Protein Structure ◽  
Membrane Protein ◽  
Structure And Function ◽  
Membrane Protein Structure ◽  
Protein Structure And Function ◽  
Lipid Environment ◽  
Membrane Pumps ◽  
And Function ◽  
P Type

Membrane protein structure and function are modulated via interactions with their lipid environment. This is particularly true for the integral membrane pumps, the P-type ATPases. These ATPases play vital roles...

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