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Theoretical investigation on peripheral ligands of oxygen-evolving center in photosystem II

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Science China(Life Sciences) 2000年第4期43卷 337-346页

作者：张纯喜潘洁李良璧匡廷云 Photosynthesis Research Center Institute of Botany Chinese Academy of Sciences Beijing 100093 China

The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted. The following conclusions are obtained: (i) both histidine and H2O molecule, bound to the two Mn ions, respectively, are vertical to the Mn2O2 plane, and maintain a large distance; (ii) the two H2O molecules cannot bind to the same Mn2O2 unit. Based on Mn-cluster structure in OEC, we theoretically predict that two H2O molecules bind to the two Mn ions at the "C"-shaped open end in S0 state, while two His residues at the closed end. Cl ion can only terminally ligate at the open end. Individual valence for the four Mn ions in S0 state is assigned.

关键词： photosynthesis oxygen-evolving center peripheral ligands (His H2O Cl) theoretical calculation.

“New-Look” Opioids: Biased ligands

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Pharmacology & Pharmacy 2018年第7期9卷 242-249页

作者： Joseph V. Pergolizzi Michael H. Ossipov Robert Taylor Robert B. Raffa NEMA Research Inc. Naples FL USA College of Medicine University of Arizona Tucson AZ USA College of Pharmacy University of Arizona Tucson AZ USA Temple University School of Pharmacy Philadelphia PA USA

Between the illicit use of opioids and attendant overdoses, and accidental overdoses with prescribed drugs, overuse of opioids has become a serious problem. At the same time, finding that fine balance between minimizing the risk of opioid misuse and abuse while at the same time providing access to treatment for patients who need pain control presents an ongoing challenge. Efforts to discover and develop better agents have led to what we term “new-look” opioids. We summarize here one such approach—known as biased ligands. By targeting a subset of GPCR signal transduction, this approach attempts to increase the separation between therapeutic and adverse effects.

关键词： Pain Analgesic Drugs Opioids G Protein-Coupled Receptors Biased ligands

Potential PET ligands for Imaging of Cerebral VPAC and PAC Receptors: Are Non-Peptide Small Molecules Superior to Peptide Compounds?

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World Journal of Neuroscience 2015年第5期5卷 364-384页

作者： Margit Pissarek INM-5 Nuclear Chemistry Institute of Neurosciences and Medicine Research Centre JülichJülich Germany

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) have been known for decades to mediate neuroendocrine and vasodilative actions via G-protein-coupled receptors of Class B. These are targets of imaging probes for positron emission tomography (PET) or single photon emission tomography (SPECT) in tumor diagnostics and tumor grading. However, they play only a subordinate role in the development of tracers for brain imaging. Difficulties in development of non-peptide ligands typical for cerebral receptors of PACAP and VIP are shared by all members of Class B receptor family. Essential landmarks have been confirmed for understanding of structural details of Class B receptor molecular signalling during the last five years. High relevance in the explanation of problems in ligand development for these receptors is admitted to the large N-terminal?ectodomain markedly different from Class A receptor binding sites and poorly suitable as orthosteric binding sites for the most small-molecule compounds. The present study is focused on the recently available receptor ligands for PAC1, VPAC1 and VPAC2 receptors as well as potential small-molecule lead structures suitable for use in PET or SPECT. Recently, biaryl, cyanothiophene and pentanamide structures with affinities in nM-range have been proposed as non-peptide ligands at VPAC1 and VPAC2 receptors. However, most of these ligands have been classified as non-competitive related to the orthosteric binding site of endogenous peptide ligands of VPAC receptors. For PAC1 receptors have been identified hydrazide compounds for which an inhibitory and potentially competitive mechanism of receptor binding has been postulated based on molecular docking studies.

关键词： Class B Receptors Vasoactive Intestinal Peptide Pituitary Adenylate Cyclase Activating Polypeptide Non-Peptide ligands PET SPECT

Bovine Endometrial Cells Mount Innate Immune Response to the Intracellular ligands CL097 and Poly(dA:dT) Indicating Roles against Uterine Viruses

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Open Journal of Animal Sciences 2017年第2期7卷 110-126页

作者： Chike F. Oguejiofor Zhangrui Cheng Ali A. Fouladi-Nashta D. Claire Wathes Department of Production and Population Health Royal Veterinary College North Mymms UK Department of Comparative Biomedical Sciences Royal Veterinary College North Mymms UK

Uterine infection and endometritis cause infertility and economic losses in the cattle industry. The innate immune response of the endometrium is critical in the elimination of pathogenic organisms that invade the uterus in postpartum cows. This study investigated the response of bovine endometrium to synthetic intracellular ligands which activate innate immunity by stimulating similar receptors to those used to recognise the presence of some viruses. Mixed primary epithelial and stromal cell cultures were treated with 5 μg/ml of CL097 (a TLR7/8 ligand) or 2 μg/ml of poly(dA:dT) (a DNA analogue) for either 6 h or 24 h. Cellular responses were assessed by the mRNA expression of 18 immune-related genes and 3 endogenous reference genes by conventional PCR followed by qRT-PCR from four replicate experiments. Bovine endometrial cells expressed the cytosolic pattern recognition receptors (PRRs) DDX58 (RIG-I), IFIH1 (MDA5) and LRRFIP1 which act as intracellular nucleic acid sensors. Neither ligand altered the expression of the extra-cytosolic pattern recognition receptors (PRRs) TLR3, TLR4, TLR7 or TLR8 whereas poly(dA:dT) treatment increased the expression of IFIH1 and DDX58. Treated cells also responded to CL097 or poly(dA:dT) with a differential up-regulation of genes involved in innate immune response including type I interferon/antiviral response (MX1, IFNAR1), antimicrobial activity (MUC1, SLPI) and cytokine activity (TNF, IL1B, IL8). Bovine endometrial cells therefore express both cytosolic and extra-cytosolic intracellular PRRs and are able to mount an innate immune response upon stimulation with intracellular ligands. This suggests an important role for these cells in the defence against viruses that may be present in the uterus in postpartum cows.

关键词： Endometrium Innate Immunity Intracellular ligands Gene Expression

Anticancer actions of PPARγ ligands:Current state and future perspectives in human lung cancer

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World Journal of Biological Chemistry 2010年第3期1卷 31-40页

作者： Jesse Roman Division of Pulmonary Critical Care and Sleep Disorders MedicineDepartment of Medicine University of Louisville School of Medicine Louisville Veterans Affairs Medical Center

Peroxisome proliferator-activated receptors(PPARs) are ligand-dependent nuclear transcription factors and members of the nuclear receptor *** the three PPARs identified to date(PPARγ,PPARβ/δ,and PPARα),PPARγ has been studied the most,in part because of the availability of PPARγagonists(also known as PPARγ ligands)and its significant effects on the management of several human diseases including type 2 diabetes,metabolic syndrome,cardiovascular disease and ***γ is expressed in many tumors including lung cancer,and its function has been linked to the process of lung cancer development, progression and *** performed in gynogenic and xenograft models of lung cancer showed decreased tumor growth and metastasis in animals treated with PPARγ ***,data are emerging from retrospective clinical studies that suggest a protective role for PPARγ ligands on the incidence of lung *** review summarizes the research being conducted in this area and focuses on the mechanisms and potential therapeutic effects of PPARγ ligands as a novel anti-lung cancer treatment strategy.

关键词： Gene expression and regulation Human lung cancer ligands Peroxisome proliferator-activated receptorγ Signaling pathways Therapy

Expression of the Epidermal Growth Factor Receptors and ligands in Paired Samples of Normal Breast Tissue, Primary Breast Carcinomas and Lymph Node Metastases

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Advances in Breast Cancer Research 2014年第2期3卷 22-37页

作者： Anja Brügmann V. Jensen J. P. Garne E. Nexo B. S. Sorensen Department of Breast Surgery Aalborg Hospital Aalborg Denmark Department of Clinical Biochemistry Aarhus University Hospital Aarhus Denmark Institute of Pathology Aalborg Hospital Aalborg Denmark Institute of Pathology Aarhus University Hospital Aarhus Denmark

Purpose: In breast cancer, the EGF receptors host an increasing number of therapeutic targets and the interactive mechanisms of actions of the receptors and their ligands justify investigation of the EGF family as an entity. Experimental design: Paired tissue samples of normal breast tissue and primary breast carcinomas were examined in a prospective study of 163 patients. A third sample was obtained from the paired ipsilateral metastatic lymph node from 58 of these patients. The mRNA expression of four EGF receptors (HER1 - HER4) and 11 activating ligands was quantified with real-time RT-PCR. Results: Expression of HER2, HER3, and HER4 mRNA was upregulated in primary carcinomas compared to normal breast tissue while HER1 was downregulated. The mRNA expression of HER3 and HER4 differed between primary breast carcinomas and lymph node metastases whereas there was no difference in the expression of HER1 and HER2. The combination of low HER3 and low HER4 expression in the primary carcinoma was significantly more frequent in lymph node-negative patients as compared to lymph node positive patients. Distinct correlation patterns of the receptors and their corresponding activating ligands appeared in both normal breast tissue and in carcinomas, notably for the HER3 and HER4 receptors and their 3 specific ligands: HB-EGF, NRG2, and NRG4. Conclusion: HER2, HER3, and HER4 showed increased mRNA expression in carcinomas and were positively correlated to each other and to specific activating ligands. Furthermore, low HER3 and HER4 expression in the carcinomas correlated to the absence of lymph node metastases.

关键词： Breast Cancer Lymph Node Metastases EGF Receptors EGF ligands RT-PCR

Synthesis and Characterization of New Chiral Monoanionic [ON] Ancillary Phenolate ligands

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International Journal of Organic Chemistry 2014年第3期4卷 182-188页

作者： Pascal Binda Leslie Glover Department of Chemistry and Forensic Science Savannah State University Savannah GA USA Science Division Southern Wesleyan University Central SC USA

Three new chiral monoanionic [ON] ancillary phenolate ligands with varying pendant arms have been synthesized in moderate to high yields (50% - 85%) via Mannich-type condensation reaction of chiral substituted phenol, formaldehyde and (+)-bis-[(R)-1-phenylethyl]amine. These new organic compounds were fully characterized via nuclear magnetic resonance spectroscopy (1H and 13C) and elemental analysis. The newly synthesized ligands are suitable candidates for metal-catalyzed ring-opening of lactones and asymmetric catalysis.

关键词： Phenolate ligands Mannich Condensation Reaction Ring-Opening Polymerization of Lactones

Synthesis, characterization, and stability of iron (III) complex ions possessing phenanthroline-based ligands

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Open Journal of Inorganic Chemistry 2013年第1期3卷 7-13页

作者： Shawnt Tosonian Charles J. Ruiz Andrew Rios Elma Frias Jack F. Eichler Department of Chemistry University of California Riverside Riverside USA

It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions.

关键词： Polypyridyl ligands Phenanthroline Iron (III) Complex Ions

Voltage-dependent block of NMDA receptors by dopamine and D1 receptor ligands

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Voltage-dependent block of NMDA receptors by dopamine and D1...