scholarly journals Fluorenone imidazolium salts as novel de Vries materials

RSC Advances ◽  
2020 ◽  
Vol 10 (40) ◽  
pp. 23999-24016
Author(s):  
Korinna Bader ◽  
Carsten Müller ◽  
Yann Molard ◽  
Angelika Baro ◽  
Philipp Ehni ◽  
...  
Keyword(s):  
Central Core ◽  
Side Chain ◽  
Head Group ◽  
Imidazolium Salts ◽  
De Vries

ILCs consisting of cationic head group–spacer–fluorenone central core–side chain show de Vries-like behaviour.

scholarly journals Prenylquinones in Human Parasitic Protozoa: Biosynthesis, Physiological Functions, and Potential as Chemotherapeutic Targets

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3721
Author(s):  
Ignasi Verdaguer ◽  
Camila Zafra ◽  
Marcell Crispim ◽  
Rodrigo Sussmann ◽  
Emília Kimura ◽  
...  
Keyword(s):  
Drug Targets ◽  
Shikimate Pathway ◽  
Mitochondrial Respiratory Chain ◽  
Side Chain ◽  
Head Group ◽  
Parasitic Protozoa ◽  
Amino Acid Degradation ◽  
Phylogenetic Origin ◽  
Metabolic Reactions ◽  
Vertebrate Hosts

Human parasitic protozoa cause a large number of diseases worldwide and, for some of these diseases, there are no effective treatments to date, and drug resistance has been observed. For these reasons, the discovery of new etiological treatments is necessary. In this sense, parasitic metabolic pathways that are absent in vertebrate hosts would be interesting research candidates for the identification of new drug targets. Most likely due to the protozoa variability, uncertain phylogenetic origin, endosymbiotic events, and evolutionary pressure for adaptation to adverse environments, a surprising variety of prenylquinones can be found within these organisms. These compounds are involved in essential metabolic reactions in organisms, for example, prevention of lipoperoxidation, participation in the mitochondrial respiratory chain or as enzymatic cofactors. This review will describe several prenylquinones that have been previously characterized in human pathogenic protozoa. Among all existing prenylquinones, this review is focused on ubiquinone, menaquinone, tocopherols, chlorobiumquinone, and thermoplasmaquinone. This review will also discuss the biosynthesis of prenylquinones, starting from the isoprenic side chains to the aromatic head group precursors. The isoprenic side chain biosynthesis maybe come from mevalonate or non-mevalonate pathways as well as leucine dependent pathways for isoprenoid biosynthesis. Finally, the isoprenic chains elongation and prenylquinone aromatic precursors origins from amino acid degradation or the shikimate pathway is reviewed. The phylogenetic distribution and what is known about the biological functions of these compounds among species will be described, as will the therapeutic strategies associated with prenylquinone metabolism in protozoan parasites.

Electron Transport from QA to Thymoquinone in a Synechococcus Oxygen-Evolving Photosystem II Preparation: Role of QB and Binding Affinity of Thymoquinone to the QB Site

1993 ◽  
Vol 48 (3-4) ◽  
pp. 174-178 ◽  
Author(s):  
Kazuhiko Satoh ◽  
Yasuhiro Kashino ◽  
Hiroyuki Koike
Keyword(s):  
Binding Affinity ◽  
Turnover Rate ◽  
Side Chain ◽  
Head Group ◽  
Binding Affinities ◽  
Ps Ii ◽  
Thermophilic Cyanobacteria ◽  
High Concentrations ◽  
Oxygen Evolving

Abstract We have recently shown that binding affinities of benzoquinones can be estimated by two methods in photosystem (PS) II particles (K. Satoh et al., Biochim. Biophys. Acta 1102, 45-52 (1992)). Using these methods we calculated the binding affinity of thymoquinone (2-methyl-5-isopropyl-p-benzoquinone) to the QB site and studied how the quinone accepts electrons in oxygen-evolving PS II particles isolated from the thermophilic cyanobacteria, Synechococcus elongatus and S. vulcanus. The results are as follows: (1) The binding constant of thymoqui­ none to the QB site determined by several methods was around 0.33 mᴍ . (2) At low thymoquinone concentrations the quinone was supposed to accept electrons via QB-plastoquinone, whereas at high concentrations the quinone seemed to bind to the QB site and accept an electron directly from Q-A. Lower rates of photoreduction of the quinone at high concentrations were attributed to a slower turnover rate of the quinone at the QB site than that of endogenous plastoquinone. (3) A model for the function of plastoquinone at the QB site, which can explain all the results, was presented. According to this model, the plastoquinone molecule at the QB site is not replaced by another plastoquinone molecule. Instead, it transfers electrons to pool plastoquinone molecules by turning over its head group but remaining its long side chain bound to the PS II complexes.

Effective dispersants for concentrated, nonaqueous suspensions

1992 ◽  
Vol 7 (10) ◽  
pp. 2884-2893 ◽  
Author(s):  
I. Sushumna ◽  
R.K. Gupta ◽  
E. Ruckenstein
Keyword(s):  
Main Chain ◽  
Side Chain ◽  
Solid Loading ◽  
Head Group ◽  
Side Chains ◽  
Concentrated Suspensions ◽  
Fatty Esters ◽  
Solids Loading ◽  
High Solids Loading ◽  
Order Of Magnitude

With the aim of identifying effective dispersants that would yield stable, high solids loading (≥60 vol.%) suspensions of oxides, carbides, or nitrides in nonaqueous carriers such as paraffinic oils, a number of dispersants were evaluated, using in most cases A16SG grade alumina from Alcoa as the filler. Among those evaluated were some common dispersants, such as menhaden fish oil and oleic acid, and commercial dispersants not commonly used in ceramic processing, such as polymeric fatty esters and petroleum sulfonates. More importantly, a few dispersants were synthesized and evaluated. The latter dispersants contained straight or cyclic (benzenic) side chains located far from the head group on 18 carbon main-chain fatty acid molecules. Among these, the dispersants with a 5–10 carbon side chain or with a benzenic side chain yielded very fluid suspensions (≥60 vol.%) compared to those with long polymeric or oligomeric side chains, or with no side chains, or the commercial dispersants; in some cases, for the same solid loading, the suspension viscosities were an order of magnitude lower with the synthesized side chain dispersants. These results indicate that molecules with an optimum side chain length located sufficiently far from the head group and an optimum backbone (main chain) constitute the most effective dispersants for concentrated suspensions. By combining the advantages provided by wider particle size distributions and by these effective dispersants, suspensions highly concentrated (up to 74 vol.%), and yet processable and “flowing” paste-like have been prepared.

Roles of head group architecture and side chain length on colorimetric response of polydiacetylene vesicles to temperature, ethanol and pH

2011 ◽  
Vol 360 (2) ◽  
pp. 565-573 ◽  
Author(s):  
Nipaphat Charoenthai ◽  
Thanutpon Pattanatornchai ◽  
Sumrit Wacharasindhu ◽  
Mongkol Sukwattanasinitt ◽  
Rakchart Traiphol
Keyword(s):  
Chain Length ◽  
Side Chain ◽  
Head Group ◽  
Side Chain Length ◽  
Colorimetric Response

scholarly journals Phospholipid analogues: side chain- and polar head group-dependent effects on phosphatidylcholine biosynthesis.

1994 ◽  
Vol 35 (4) ◽  
pp. 625-632
Author(s):  
C.C. Geilen ◽  
A. Haase ◽  
T. Wieder ◽  
D. Arndt ◽  
R. Zeisig ◽  
...  
Keyword(s):  
Side Chain ◽  
Head Group ◽  
Polar Head Group ◽  
Polar Head ◽  
Phosphatidylcholine Biosynthesis

Molecular Modelling Studies on the Binding of Phenylurea Inhibitors to the D 1 Protein of Photosystem II

1990 ◽  
Vol 45 (5) ◽  
pp. 379-387 ◽  
Author(s):  
John Bowyer ◽  
Mark Hilton ◽  
Julian Whitelegge ◽  
Philip Jewess ◽  
Patrick Camilleri ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Molecular Model ◽  
Binding Domain ◽  
Side Chain ◽  
Head Group ◽  
Reaction Centre ◽  
Binding Interactions ◽  
Reaction Centres ◽  
Molecular Modelling Studies ◽  
Modelling Studies

Abstract A hypothetical molecular model of part of the D 1 protein of photosystem II, based on the analogous portion of the L subunit of the Rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (N,N-dimethyl-carbamoyl)4 -amino-4 ′-chloro-trans-stilbene) (I) to the QB site. The inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/D 1 complex was energy minimized. The gross orientation of the inhibitor placed the dimethylurea moiety towards the predicted binding domain of the plastoquinone head group, and the stilbene moiety directed along the quinone isoprenoid side chain binding domain, suggesting a similar pathway of approach of the two molecules from the membrane into the binding site. Binding interactions of the inhibitor included hydrogen bonds to the side chain hydroxyl of ser 264 and the peptide carbonyl group of ala 251, with the side chain hydroxyl of ser 268 as an alternative ligand. Numerous hydrophobic contacts were also possible. Although phenylureas do not bind to reaction centres of Rp. viridis, many of the binding interactions to D1 could also be detected in Rp. viridis. However, the β-CH2 and δ-CO2-groups of glu 212 in Rp. viridis are located in the corresponding region of D1 occupied by the dimethylurea moiety of the inhibitor in our model of its binding to D 1. This may explain why diuron (DCMU) does not bind to Rp. viridis reaction centres.

scholarly journals New aspects of microbial vitamin K2 production by expanding the product spectrum

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Zimeng Zhang ◽  
Linxia Liu ◽  
Chuan Liu ◽  
Yumei Sun ◽  
Dawei Zhang
Keyword(s):  
Metabolic Engineering ◽  
Small Molecules ◽  
Shikimate Pathway ◽  
Vitamin K2 ◽  
Side Chain ◽  
Head Group ◽  
Depth Information ◽  
Product Spectrum ◽  
Different Types ◽  
Membrane Engineering

AbstractVitamin K2 (menaquinone, MK) is an essential lipid-soluble vitamin with critical roles in blood coagulation and bone metabolism. Chemically, the term vitamin K2 encompasses a group of small molecules that contain a common naphthoquinone head group and a polyisoprenyl side chain of variable length. Among them, menaquinone-7 (MK-7) is the most potent form. Here, the biosynthetic pathways of vitamin K2 and different types of MK produced by microorganisms are briefly introduced. Further, we provide a new aspect of MK-7 production, which shares a common naphthoquinone ring and polyisoprene biosynthesis pathway, by analyzing strategies for expanding the product spectrum. We review the findings of metabolic engineering strategies targeting the shikimate pathway, polyisoprene pathway, and menaquinone pathway, as well as membrane engineering, which provide comprehensive insights for enhancing the yield of MK-7. Finally, the current limitations and perspectives of microbial menaquinone production are also discussed. This article provides in-depth information on metabolic engineering strategies for vitamin K2 production by expanding the product spectrum.

Effect of plasma membrane fluidity on serotonin transport by endothelial cells

1987 ◽  
Vol 253 (5) ◽  
pp. C672-C678 ◽  
Author(s):  
E. R. Block ◽  
D. Edwards
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Pulmonary Artery ◽  
Membrane Fluidity ◽  
Vaccenic Acid ◽  
Membrane Lipid ◽  
Side Chain ◽  
Head Group ◽  
Plasma Membrane Fluidity ◽  
Serotonin Transport

To evaluate the effect of plasma membrane fluidity of lung endothelial cells on serotonin transport, porcine pulmonary artery endothelial cells were incubated for 3 h with either 0.1 mM cholesterol hemisuccinate, 0.1 mM cis-vaccenic acid, or vehicle (control), after which plasma membrane fluidity and serotonin transport were measured. Fluorescence spectroscopy was used to measure fluidity in the plasma membrane. Serotonin uptake was calculated from the disappearance of [14C]-serotonin from the culture medium. Cholesterol decreased fluidity in the subpolar head group and central and midacyl side-chain regions of the plasma membrane and decreased serotonin transport, whereas cis-vaccenic acid increased fluidity in the central and midacyl side-chain regions of the plasma membrane and also increased serotonin transport. Cis-vaccenic acid had no effect on fluidity in the subpolar head group region of the plasma membrane. These results provide evidence that the physical state of the central and midacyl chains within the pulmonary artery endothelial cell plasma membrane lipid bilayer modulates transmembrane transport of serotonin by these cells.

Identification of quinoxalin-2(1H)-one derivatives as a novel class of multifunctional aldose reductase inhibitors

2019 ◽  
Vol 11 (23) ◽  
pp. 2989-3004 ◽  
Author(s):  
Xin Hao ◽  
Xiangyu Qin ◽  
Xin Zhang ◽  
Bing Ma ◽  
Gang Qi ◽  
...  
Keyword(s):  
Aldose Reductase ◽  
Side Chain ◽  
Head Group ◽  
Binding Modes ◽  
Aldose Reductase Inhibition ◽  
Aldose Reductase Inhibitors ◽  
Reductase Inhibitors ◽  
Bioisosteric Replacement ◽  
Antioxidant Potency ◽  
And Oxidative Stress

Aim: Targeting aldose reductase and oxidative stress with quinoxalin-2(1 H)-one derivatives having a 1-hydroxypyrazole head as the bioisosteric replacement of carboxylic acid. Methodology & results: Aldose reductase inhibition, selectivity and antioxidant potency of all the synthesized compounds were evaluated, and binding modes were studied by molecular docking. Most of the derivatives showed potent and selective aldose reductase inhibition, and among them 13d was the most active (IC50 = 0.107 μM), suggesting success of the bioisosteric strategy. Phenolic 3,4-dihydroxyl compound 13f showed strong antioxidant ability even comparable to that of the well-known antioxidant Trolox. Conclusion: The present study identified the excellent bioisostere of the 1-hydroxypyrazole head group along with phenolic hydroxyl and vinyl spacer in C3 side chain on constructing quinoxalinone-based multifunctional aldose reductase inhibitors.

De Vries smectic A phase formed by a liquid crystal side chain copolymer? A13C NMR study

2005 ◽  
Vol 32 (10) ◽  
pp. 1307-1316 ◽  
Author(s):  
L. Naji ◽  
R. Stannarius ◽  
S. Grande ◽  
M. Rössle ◽  
R. Zentel
Keyword(s):  
Liquid Crystal ◽  
Side Chain ◽  
Smectic A ◽  
Nmr Study ◽  
Smectic A Phase ◽  
De Vries
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