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101.
Min Xu Fei Zhang Zhuo Cheng Ghader Bashiri Jing Wang Jiali Hong Yemin Wang Lijun Xu Xuefei Chen Sheng-Xiong Huang Shuangjun Lin Zixin Deng Meifeng Tao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18185-18191
Lantibiotics are a type of ribosomally synthesized and post-translationally modified peptides (termed lanthipeptides) with often potent antimicrobial activity. Herein, we report the discovery of a new lantibiotic, lexapeptide, using the library expression analysis system (LEXAS) approach. Lexapeptide has rare structural modifications, including N-terminal (N,N)-dimethyl phenylalanine, C-terminal (2-aminovinyl)-3-methyl-cysteine, and d -Ala. The characteristic lanthionine moiety in lexapeptide is formed by three proteins (LxmK, LxmX, and LxmY), which are distinct from enzymes known to be involved in lanthipeptide biosynthesis. Furthermore, a novel F420H2-dependent reductase (LxmJ) from the lexapeptide biosynthetic gene cluster (BGC) is identified to catalyze the reduction of dehydroalanine to install d -Ala. Our findings suggest that lexapeptide is the founding member of a new class of lanthipeptides that we designate as class V. We also identified further class V lanthipeptide BGCs in actinomycetes and cyanobacteria genomes, implying that other class V lantibiotics await discovery. 相似文献
102.
Dr. Mozhgan Khorasani Motlagh Dr. Meissam Noroozifar Dr. Rana N. S. Sodhi Prof. Heinz-Bernhard Kraatz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(51):e202200953
An enzymatic biosensor has been developed for the determination of selenate (SeO42−), in which selenate reductase (SeR) is chemically attached to a gold disk electrode by lipoic acid N-hydroxysuccinimide ester as linker, allowing the catalytic reduction of the SeO42− to SeO32−. Modification of the gold electrode was characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and electrochemistry. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed in different buffers for selenate determination. Under optimum conditions, the calibration curve was linear over the range 7.0–3900.0 μg L−1 with limits of detection and quantification of 4.97 and 15.56 μg L−1, respectively. The possible interference of the relevant oxyanions SO42−, NO3−, NO2−, PO43− and AsO43− in the determination of SeO42− was studied. Finally, the proposed biosensor was used to determine SeO42− with recovery between 95.2 and 102.4 % in different real water samples. 相似文献
103.
Prof. Dmitry Dar'in Dr. Grigory Kantin Dr. Evgeny Chupakhin Dr. Vladimir Sharoyko Prof. Mikhail Krasavin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(31):8221-8227
α-Diazo homophotalimides were reacted with various propiolic acids on Rh2(esp)2 catalysis. The resulting propiolate esters were transformed into novel, heterocyclic Δα,β-spirobutenolides in good to excellent product yields. The approach represents a fundamentally novel entry into natural-like Δα,β-spirobutenolides present in many biologically active natural products as well as fully synthetic compounds endowed with diverse biological activities. The Δα,β-spirobutenolides thus obtained were shown to inhibit thioredoxin reductase, a selenocysteine enzyme target for cancer. Moreover, for the best compound in the series (TrxR IC50 1.49±0.08 μM), by using MALDI-TOF mass-spectrometry it was shown that it selectively binds selenocysteine in the presence of a 10-fold excess of cysteine. This validates the new compound as a promising lead for anticancer therapy development. 相似文献
104.
Chiao‐Yuan Fan Hsiu‐Chuan Chou Yi‐Wen Lo Yueh‐Feng Wen Yi‐Chih Tsai Haimei Huang Hong‐Lin Chan 《Electrophoresis》2013,34(24):3305-3314
Glutathione reductase (GR), a cytosolic protein, plays a vital role in maintaining a correct redox status in cells. However, comprehensive investigations of GR‐modulated cellular responses, including protein level alteration and redox regulation, have yet to be performed. In this study, we cultured a human lung adenocarcinoma line transfected with empty pLKO.1 vector as a control, CL1‐0shControl, and its GR‐knockdown derivative, CL1‐0shΔGR, to evaluate differential protein level alteration and redox regulation of these two cell lines. We identified 34 spots that exhibited marked changes in intensities, and 13 proteins showing significant changes in thiol reactivity, in response to GR depletion. Several proteins involved in redox regulation, calcium signaling, cytoskeleton regulation, and protein folding showed significant changes in expression, whereas proteins involved in redox regulation, protein folding, and glycolysis displayed changes in thiol reactivity. Interestingly, GR knockdown induces peroxiredoxin‐1 overexpression in the air‐exposed tissue and high oxygen consuming tissue such as cornea and liver, but not in the low oxygen consuming tissues such as breast and uterine. In summary, we used a comprehensive lung adenocarcinoma based proteomic approach for identifying GR‐modulated protein expression alteration and redox modification. Based on our research, this is the first comprehensive proteomic and redox‐proteomic analysis used to investigate the role of GR in a mammalian cell model. 相似文献
105.
Amr Ali Attia Radu Silaghi‐Dumitrescu 《International journal of quantum chemistry》2014,114(10):652-665
A computational study based on density functional theory was undertaken to identify possible reaction pathways for the formation and decomposition of peroxynitrite at models of the active sites of the nonheme superoxide scavenging enzymes superoxide reductase (SOR) and iron superoxide dismutase (FeSOD). Two peroxynitrite isomers and their possible protonated states were investigated, namely Fe? OONO?, Fe? N(O)OO?, Fe? OONOH, and Fe? N(O)OOH. Peroxynitrite formation at the active sites was assumed by either the interaction of a peroxynitrite cis/trans anion with the pentacoordinated iron active site or the interaction between a nitric oxide bound adduct and superoxide; both scenarios were found to be facile for all models investigated. The ferrous adducts of the Fe? OONO?isomer were found to undergo instant heterolytic cleavage of the O? ONO bond to yield nitrite, whereas for the ferric adducts, the homolytic cleavage of the O? ONO bond to yield nitrogen dioxide was found to be energetically facile. For the Fe? N(O)OO? isomer, the active site models of FeSOD and SOR were only able to accommodate the cis isomer of peroxynitrite. Ferric adducts of the cis Fe? OONO? isomer were found to be energetically more stable than their trans counterparts and were also more stable than the cis adducts of the Fe? N(O)OO? isomer; conversely, the protonated forms of all adducts of the Fe? OONOH isomer were found to be lower in energy than their equivalent Fe? N(O)OOH adducts. Multiple reaction pathways for the decomposition of the formed peroxynitrite adducts (whether the anions or the protonated forms) were proposed and explored. The energy requirements for the decomposition processes ranged from exothermic to highly demanding depending on the peroxynitrite isomer, the type of model (whether an SOR or FeSOD active site), and the oxidation state of iron. © 2014 Wiley Periodicals, Inc. 相似文献
106.
A concise and stereocontrolled synthesis of rosuvastatin calcium has been accomplished, with the key steps including a Keck enantioselective allylation of chloroacetaldehyde with allyltributylstannane to install 5R-stereocenter and a VO(acac)2-catalyzed syn-diastereoselective epoxidation of (S)-1-chloropent-4-en-2-ol to set the requisite 3R-chirality. 相似文献
107.
Anirban Bhandari Saikat Mishra Ram Chandra Maji Akhilesh Kumar Marilyn M. Olmstead Apurba K. Patra 《Angewandte Chemie (International ed. in English)》2020,59(23):9177-9185
According to the well‐accepted mechanism, methyl‐coenzyme M reductase (MCR) involves Ni‐mediated thiolate‐to‐disulfide conversion that sustains its catalytic cycle of methane formation in the energy saving pathways of methanotrophic microbes. Model complexes that illustrate Ni‐ion mediated reversible thiolate/disulfide transformation are unknown. In this paper we report the synthesis, crystal structure, spectroscopic properties and redox interconversions of a set of NiII complexes comprising a tridentate N2S donor thiol and its analogous N4S2 donor disulfide ligands. These complexes demonstrate reversible NiII‐thiolate/NiII‐disulfide (both bound and unbound disulfide‐S to NiII) transformations via thiyl and disulfide monoradical anions that resemble a primary step of MCR's catalytic cycle. 相似文献
108.
Rational protein design is a powerful strategy, not only for revealing the structure and function relationship of natural metallo-proteins, but also for creating artificial metalloproteins with improved properties and functions. Myoglobin (Mb), a small heme protein created by nature with diverse functions, has been shown to be an ideal scaffold for rational protein design. The progress reviewed herein includes fine-tuning its native functions of O2 binding and transport, peroxidase activity and nitrite reductase (NIR) activity, and rational expanding its functionalities to peroxygenase, heme-copper oxidase (HCO), nitric oxide reductase (NOR), as well as hydroxylamine reductase. These studies have enhanced our understanding of how metalloproteins work in nature, and provided insights for rational design of functional metalloproteins for practical applications in the future. 相似文献
109.
Shuyun Zhu Xian-en Zhao Wei Zhang Zhongyuan Liu Wenjing Qi Saima Anjum Guobao Xu 《Analytica chimica acta》2013
Fluorescent silver nanoclusters stabilized by DNA (DNA-AgNCs) exhibit distinct response rates to thiol and disulfide. Glutathione reductase can catalyze the reduction of the oxidized glutathione (GSSG) quickly to reduced glutathione (GSH) in the presence of β-nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt hydrate (NADPH). Consequently, DNA-AgNCs can serve as a new fluorescent platform for assaying the glutathione reductase (GR) activity. This newly proposed assay has a high sensitivity and a good selectivity toward GR. The GR activity can be detected in the range of 0.2–2.0 mU mL−1 with a minimum detectable concentration of 0.2 mU mL−1. Pepsin, lysozyme, trypsin, avidin, thrombin, myoglobin, and BSA have little effect on the fluorescence intensity of DNA-AgNCs. The GR activity assay is successfully used to monitor the inhibition of GR activity by a typical inhibitor 1,3-bis(2-chloroethyl)-1-nitrosourea. 相似文献
110.
Fabio Zuccotto Andrew C.R Martin Roman A. Laskowski Janet M. Thornton Ian H. Gilbert 《Journal of computer-aided molecular design》1998,12(3):241-257
Dihydrofolate reductase has successfully been used as a drug target in the area of anti-cancer, anti-bacterial and anti-malarial chemotherapy. Little has been done to evaluate it as a drug target for treatment of the trypanosomiases and leishmaniasis. A crystal structure of Leishmania major dihydrofolate reductase has been published. In this paper, we describe the modelling of Trypanosoma cruzi and Trypanosoma brucei dihydrofolate reductases based on this crystal structure. These structures and models have been used in the comparison of protozoan, bacterial and human enzymes in order to highlight the different features that can be used in the design of selective anti-protozoan agents. Comparison has been made between residues present in the active site, the accessibility of these residues, charge distribution in the active site, and the shape and size of the active sites. Whilst there is a high degree of similarity between protozoan, human and bacterial dihydrofolate reductase active sites, there are differences that provide potential for selective drug design. In particular, we have identified a set of residues which may be important for selective drug design and identified a larger binding pocket in the protozoan than the human and bacterial enzymes. 相似文献