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Sekwon Kim - One of the best experts on this subject based on the ideXlab platform.
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characterization of the in vitro effects of gallic acid grafted Chitooligosaccharides in the suppression of ags human gastric cancer cell proliferation
RSC Advances, 2017Co-Authors: Bomi Ryu, Soyeon Kim, Wonsuk Kim, Donggyu Kim, Sekwon KimAbstract:Gastric cancer is the second most common cause of cancer-related deaths in the world. In this study, a bioactive derivative of chitooligosaccharide, named gallic acid-grafted-chitooligosaccharide (G-COS), was evaluated for its capabilities against the proliferation of AGS human gastric cancer cells. It was found that G-COS treatment caused significant inhibition of gastric cancer cell growth at concentrations of 200 and 400 μg mL−1. The anti-growth effect of G-COS in AGS cells was characterized using flow cytometry, fluorescence microscopy, DNA fragmentation and evaluation of protein expression. Notably, G-COS-induced apoptosis was related to the increase in the expression of p53, p21, Bax, and caspases (-9 and -3) and the decrease in the activation of Bcl-2, p-IκB-α and NF-κB (p50 and p65). These findings indicate that G-COS has potential to be applied in the treatment of gastric cancer as a cancer chemopreventative agent.
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gallic acid grafted Chitooligosaccharides suppress antigen induced allergic reactions in rbl 2h3 mast cells
European Journal of Pharmaceutical Sciences, 2012Co-Authors: Daihung Ngo, Sekwon KimAbstract:Abstract In this study, a bioactive derivative of Chitooligosaccharides (3–5 kDa) was synthesized via grafting of gallic acid onto Chitooligosaccharides (G-COS) to enhance anti-allergic activity. Hence, G-COS was evaluated for its capabilities against allergic reactions in RBL-2H3 mast cells sensitized with dinitrophenyl-specific immunoglobulin E antibody and stimulated by antigen dinitrophenyl-bovine serum albumin. It was revealed that G-COS exhibited significant inhibition on histamine release and production as well as intracellular Ca 2+ elevation at the concentration of 200 μg/ml. Likewise, the suppressive effects of G-COS on expression and production of interleukin (IL)-4 and tumor necrosis factor (TNF)-α were evidenced. Moreover, G-COS treatment caused a remarkable blockade on degradation of inhibitory κB-α (IκB-α) protein, translocation of nuclear factor (NF)-κB, and phosphorylation of mitogen-activated protein kinases (MAPKs). Notably, the inhibitory activities of G-COS on allergic reactions were found as a consequence of suppression of FceRI expression in antigen-stimulated cells. Accordingly, G-COS was suggested to be a promising candidate of novel inhibitors against allergic reactions.
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Chitooligosaccharides as potential nutraceuticals production and bioactivities
Advances in food and nutrition research, 2012Co-Authors: Sekwon KimAbstract:Chitooligosaccharide (COS), a derivative of chitosan, can be produced by either chemical or enzymatic hydrolysis. Looking back through past research, several technological approaches have been taken to prepare COSs, and enzymatic approaches are favorable due to their environmentally friendly methods, safety, and a lack of toxicity. Similar to chitosan, COSs can also be considered potential nutraceuticals due to their versatile biological activities, water-soluble properties, and absorption properties in the intestine. Therefore, this chapter provides certain methods for the preparation of COSs and addresses their biological properties such as antihypertensive, antioxidant, antitumor, antimicrobial, and other select biological activities.
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anti proliferative effect of aminoderivatized Chitooligosaccharides on ags human gastric cancer cells
Process Biochemistry, 2010Co-Authors: Mustafa Zafer Karagozlu, Jungae Kim, Fatih Karadeniz, Changsuk Kong, Sekwon KimAbstract:In this study, the ability of aminoethylation of chitooligosaccharide (COS) to inhibit the proliferation of AGS human gastric adenocarcinoma cells was evaluated. Aminoderivatized COSs, aminoethyl-chitooligosaccharide (AE-COS), dimethyl aminoethyl-chitooligosaccharide (DMAE-COS) and diethyl aminoethyl-chitooligosaccharide (DEAE-COS), were synthesized and confirmed by their IR spectra results in comparison to previous study. Aminoderivatized Chitooligosaccharides-induced cell death was characterized by cell viability assay, changes in nuclear morphology and changes in cell morphology. According to our results, all aminoderivatized COSs significantly induced cell death in AGS gastric cancer cells. Moreover, protein and gene expression levels of important regulators involved in apoptosis pathway such as Bcl-2, Bax, p53 and p21 were examined using RT-PCR and Western blot analysis. Aminoderivatized COSs showed dose- and time-dependent inhibition of AGS cancer cell proliferation. AE-COS and DEAE-COS showed the higher apoptotic activity than DMAE-COS. The present results suggest all three kinds of water-soluble aminoderivatized COSs have a promising potential as valuable as cancer chemopreventive agents.
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anti hiv 1 activity of low molecular weight sulfated Chitooligosaccharides
Carbohydrate Research, 2010Co-Authors: Murat Artan, Fatih Karadeniz, Mustafa Zafer Karagozlu, Moonmoo Kim, Sekwon KimAbstract:Chitooligosaccharides are nontoxic and water-soluble compounds obtained by enzymatic degradation of chitosan, which is derived from chitin by a deacetylation process. Chitooligosaccharides possess broad range of activities such as antitumour, antifungal, antibacterial activities. Sulfated Chitooligosaccharides (SCOSs) with different molecular weights were synthesized by a random sulfation reaction. In the present study, anti-HIV-1 properties of SCOSs and the impact of molecular weight on their inhibitory activity were investigated. SCOS III (MW 3-5 kDa) was found to be the most effective compound to inhibit HIV-1 replication. At nontoxic concentrations, SCOS III exhibited remarkable inhibitory activities on HIV-1-induced syncytia formation (EC(50) 2.19 microg/ml), lytic effect (EC(50) 1.43 microg/ml), and p24 antigen production (EC(50) 4.33 microg/ml and 7.76 microg/ml for HIV-1(RF) and HIV-1(Ba-L), respectively). In contrast, unsulfated Chitooligosaccharides showed no activity against HIV-1. Furthermore, it was found that SCOS III blocked viral entry and virus-cell fusion probably via disrupting the binding of HIV-1 gp120 to CD4 cell surface receptor. These results suggest that sulfated Chitooligosaccharides represent novel candidates for the development of anti-HIV-1 agent.
Musti J Swamy - One of the best experts on this subject based on the ideXlab platform.
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purification biochemical biophysical characterization and chitooligosaccharide binding to bgl24 a new pp2 type phloem exudate lectin from bottle gourd lagenaria siceraria
International Journal of Biological Macromolecules, 2020Co-Authors: Saradamoni Mondal, Musti J SwamyAbstract:Abstract Phloem Protein 2 (PP2), highly abundant in the sieve elements of plants, plays a significant role in wound sealing and anti-pathogenic responses. In this study, we report the purification and characterization of a new PP2-type lectin, BGL24 from the phloem exudate of bottle gourd (Lagenaria siceraria). BGL24 is a homodimer with a subunit mass of ~24 kDa and exhibits high specificity for Chitooligosaccharides. The isoelectric point of BGL24 was estimated from zeta potential measurements as 5.95. Partial amino acid sequence obtained by mass spectrometric studies indicated that BGL24 exhibits extensive homology with other PP2-type phloem exudate lectins. CD spectroscopic measurements revealed that the lectin contains predominantly β-sheets, with low α-helical content. CD spectroscopic and DSC studies showed that BGL24 exhibits high thermal stability with an unfolding temperature of ~82 °C, and that its secondary structure is essentially unaltered between pH 3.0 and 8.0. Fluorescence titrations employing 4-methylumbelliferyl-β-D-N,N′,N″-triacetylchitotrioside as an indicator ligand revealed that the association constants for BGL24-chitooligosaccharide interaction increase considerably when the ligand size is increased from chitotriose to chitotetraose, whereas only marginal increase was observed for chitopentaose and chitohexaose. BGL24 exhibited moderate cytotoxicity against MDA-MB-231 breast cancer cells, whereas its effect on normal splenocytes was marginal.
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a new chitooligosaccharide specific lectin from snake gourd trichosanthes anguina phloem exudate purification physico chemical characterization and thermodynamics of saccharide binding
Biochimie, 2011Co-Authors: Akkaladevi Narahari, Pavan Kumar Nareddy, Musti J SwamyAbstract:Abstract A new lectin has been purified to homogeneity from the phloem exudate of snake gourd (Trichosanthes anguina) by affinity chromatography on chitin. The snake gourd phloem lectin (SGPL) specifically binds Chitooligosaccharides and their inhibitory potency increased with increase in size. PAGE and SDS-PAGE studies indicate that SGPL is a heterodimer, in which the two subunits (48 and 53 kDa) are joined by disulfide bonds. Consistent with this, electrospray-ionization mass spectrum yielded the exact mass of the protein as 104,621.8 Daltons. CD studies showed that SGPL contains about 9% α-helix, 39% β-sheet, 20% β-turns and 32% unordered structures and that saccharide binding does not significantly affect its secondary and tertiary structures. Titration calorimetric studies indicate that the dimeric lectin binds two ligand molecules [(GlcNAc)3–6] with association constants determined at 25 °C being 1.7 × 105 and 3.6 × 105 M−1, for chitotriose and chitohexaose, respectively. Binding of all the Chitooligosaccharides is governed by enthalpic forces, whereas the contribution from binding entropies was unfavorable. These results suggest that the SGPL-saccharide interaction is stabilized by hydrogen bonding and van der Waals’ interactions. Enthalpy–entropy compensation was observed for the SGPL-chitooligosaccharide interaction, suggesting that water molecules play a key role in the binding process.
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isothermal titration calorimetric and computational studies on the binding of Chitooligosaccharides to pumpkin cucurbita maxima phloem exudate lectin
Journal of Physical Chemistry B, 2011Co-Authors: Akkaladevi Narahari, Pavan Kumar Nareddy, Hitesh Singla, Gopalakrishnan Bulusu, Avadhesha Surolia, Musti J SwamyAbstract:The interaction of Chitooligosaccharides [(GlcNAc) 2−6 ] with pumpkin phloem exudate lectin (PPL) was investigated by isothermal titration calorimetry and computational methods. The dimeric PPL binds to (GlcNAc) 3−5 with binding constants of 1.26−1.53 × 10 5 M −1 at 25 °C, whereas chitobiose exhibits approximately 66-fold lower affinity. Interestingly, chitohexaose shows nearly 40-fold higher affinity than chitopentaose with a binding constant of 6.16 × 10 6 M −1 . The binding stoichiometry decreases with an increase in the oligosaccharide size from 2.26 for chitobiose to 1.08 for chitohexaose. The binding reaction was essentially enthalpy driven with negative entropic contribution, suggesting that hydrogen bonds and van der Waals’ interactions are the main factors that stabilize PPL−saccharide association. The three-dimensional structure of PPL was predicted by homology modeling, and binding of Chitooligosaccharides was investigated by molecular docking and molecular dynamics simulations, which showed that the protein binding pocket can accommodate up to three GlcNAc residues, whereas additional residues in chitotetraose and chitopentaose did not exhibit any interactions with the binding pocket. Docking studies with chitohexaose indicated that the two triose units of the molecule could interact with different protein binding sites, suggesting formation of higher order complexes by the higher oligomers of GlcNAc by their simultaneous interaction with two protein molecules.
Kasper Røjkjær Andersen - One of the best experts on this subject based on the ideXlab platform.
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A combination of chitooligosaccharide and lipochitooligosaccharide recognition promotes arbuscular mycorrhizal associations in Medicago truncatula
Nature Communications, 2019Co-Authors: Feng Feng, Sebastien Fort, Jongho Sun, Guru Radhakrishnan, Tak Lee, Zoltán Bozsóki, Aleksander Gavrin, Kira Gysel, Mikkel Thygesen, Kasper Røjkjær AndersenAbstract:Plants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce Chitooligosaccharides (COs) and lipo-Chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment.
Pablo Tornero - One of the best experts on this subject based on the ideXlab platform.
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The grapevine (Vitis vinifera) LysM receptor kinases VvLYK1-1 and VvLYK1-2 mediate chitooligosaccharide-triggered immunity
Plant Biotechnology Journal, 2019Co-Authors: Daphnée Brulé, Mc Heloir, Clizia Villano, Laura J. Davies, Lucie Trdá, Justine Claverie, Annick Chiltz, Marielle Adrian, Benoît Darblade, Pablo TorneroAbstract:Chitin, a major component of fungal cell walls, is a well-known pathogen-associated molecular pattern (PAMP) that triggers defense responses in several mammal and plant species. Here, we show that two Chitooligosaccharides, chitin and chitosan, act as PAMPs in grapevine (Vitis vinifera) as they elicit immune signalling events, defense gene expression and resistance against fungal diseases. To identify their cognate receptors, the grapevine family of LysM receptor kinases (LysM-RKs) was annotated and their gene expression profiles were characterized. Phylogenetic analysis clearly distinguished three V. vinifera LysM-RKs (VvLYKs) located in the same clade as the Arabidopsis CHITIN ELICITOR RECEPTOR KINASE1 (AtCERK1), which mediates chitin-induced immune responses. The Arabidopsis mutant Atcerk1, impaired in chitin perception, was transformed with these three putative orthologous genes encoding VvLYK1-1, -2, or -3 to determine if they would complement the loss of AtCERK1 function. Our results provide evidence that VvLYK1-1 and VvLYK1-2, but not VvLYK1-3, functionally complement the Atcerk1 mutant by restoring chitooligosaccharide-induced MAPK activation and immune gene expression. Moreover, expression of VvLYK1-1 in Atcerk1 restored penetration resistance to the non-adapted grapevine powdery mildew (Erysiphe necator). On the whole, our results indicate that the grapevine VvLYK1-1 and VvLYK1-2 participate in chitin- and chitosan-triggered immunity and that VvLYK1-1 plays an important role in basal resistance against E. necator.
Wipa Suginta - One of the best experts on this subject based on the ideXlab platform.
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single channel properties sugar specificity and role of chitoporin in adaptive survival of vibrio cholerae type strain o1
Journal of Biological Chemistry, 2020Co-Authors: Hannadige Sasimali Madusanka Soysa, Anuwat Aunkham, Albert Schulte, Wipa SugintaAbstract:Vibrio cholerae is a Gram-negative, facultative anaerobic bacterial species that causes serious disease and can grow on various carbon sources, including chitin polysaccharides. In saltwater, its attachment to chitin surfaces not only serves as the initial step of nutrient recruitment but is also a crucial mechanism underlying cholera epidemics. In this study, we report the first characterization of a chitooligosaccharide-specific chitoporin, VcChiP, from the cell envelope of the V. cholerae type strain O1. We modeled the structure of VcChiP, revealing a trimeric cylinder that forms single channels in phospholipid bilayers. The membrane-reconstituted VcChiP channel was highly dynamic and voltage induced. Substate openings O1', O2', and O3', between the fully open states O1, O2, and O3, were polarity selective, with nonohmic conductance profiles. Results of liposome-swelling assays suggested that VcChiP can transport monosaccharides, as well as Chitooligosaccharides, but not other oligosaccharides. Of note, an outer-membrane porin (omp)-deficient strain of Escherichia coli expressing heterologous VcChiP could grow on M9 minimal medium supplemented with small Chitooligosaccharides. These results support a crucial role of chitoporin in the adaptive survival of bacteria on chitinous nutrients. Our findings also suggest a promising means of vaccine development based on surface-exposed outer-membrane proteins and the design of novel anticholera agents based on chitooligosaccharide-mimicking analogs.
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molecular uptake of Chitooligosaccharides through chitoporin from the marine bacterium vibrio harveyi
PLOS ONE, 2013Co-Authors: Wipa Suginta, Albert Schulte, Watcharin Chumjan, Kozhinjampara R Mahendran, Petra Janning, Mathias WinterhalterAbstract:Background Chitin is the most abundant biopolymer in marine ecosystems. However, there is no accumulation of chitin in the ocean-floor sediments, since marine bacteria Vibrios are mainly responsible for a rapid turnover of chitin biomaterials. The catabolic pathway of chitin by Vibrios is a multi-step process that involves chitin attachment and degradation, followed by chitooligosaccharide uptake across the bacterial membranes, and catabolism of the transport products to fructose-6-phosphate, acetate and NH3.
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crystal structures of vibrio harveyi chitinase a complexed with Chitooligosaccharides implications for the catalytic mechanism
Journal of Structural Biology, 2008Co-Authors: Chomphunuch Songsiriritthigul, Supansa Pantoom, Adeleke H Aguda, Robert Robinson, Wipa SugintaAbstract:Abstract This research describes four X-ray structures of Vibrio harveyi chitinase A and its catalytically inactive mutant (E315M) in the presence and absence of substrates. The overall structure of chitinase A is that of a typical family-18 glycosyl hydrolase comprising three distinct domains: (i) the amino-terminal chitin-binding domain; (ii) the main catalytic (α/β) 8 TIM-barrel domain; and (iii) the small (α + β) insertion domain. The catalytic cleft of chitinase A has a long, deep groove, which contains six chitooligosaccharide ring-binding subsites (−4)(−3)(−2)(−1)(+1)(+2). The binding cleft of the ligand-free E315M is partially blocked by the C -terminal (His) 6 -tag. Structures of E315M-chitooligosaccharide complexes display a linear conformation of pentaNAG, but a bent conformation of hexaNAG. Analysis of the final 2 F o − F c omit map of E315M-NAG6 reveals the existence of the linear conformation of the hexaNAG at a lower occupancy with respect to the bent conformation. These crystallographic data provide evidence that the interacting sugars undergo conformational changes prior to hydrolysis by the wild-type enzyme.