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Ida Lindström, Eva Andersson, Jakob Dogan
Intrinsically disordered proteins (IDPs) are common in eukaryotes. However, relatively few experimental studies have addressed the nature of the rate-limiting transition state for the coupled binding and folding reactions involving IDPs. By using site-directed mutagenesis in combination with kinetics measurements we have here characterized the transition state for binding between the globular TAZ1 domain of CREB binding protein and the intrinsically disordered C-terminal activation domain of Hif-1α (Hif-1α CAD)...
May 18, 2018: Scientific Reports
Xuemei Liu, Pei Hu, Yongsheng Wang, Xizhu Wang, Jinghua Huang, Jin Li, Cheng Li, Hongyun Wang, Ji Jiang
Monocyte locomotion inhibitory factor (MLIF, Met-Gln-Cys-Asn-Ser), a pentapeptide with anti-inflammatory activity, was developed for neural protection in acute ischemic stroke. Determination of MLIF in human plasma samples is of great importance for pharmacokinetic evaluation in clinical studies. A reliable and sensitive method based on ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) was established for the measurement of MLIF in human plasma. Instability of peptide in matrix was the primary challenge in method development, which was properly resolved by addition of acidification reagents like sulfuric acid...
April 10, 2018: Journal of Pharmaceutical and Biomedical Analysis
Hui Wang, Zhuang Xue, Zhaoqun Liu, Weilin Wang, Feifei Wang, Ying Wang, Lingling Wang, Linsheng Song
C-type lectins (CTLs) are Ca2+ dependent carbohydrate-binding proteins that share structural homology in their carbohydrate-recognition domains (CRDs). In the present study, a novel CTL was identified from sea cucumber Apostichopus japonicus (named as AjCTL-2). The deduced amino acid sequence of AjCTL-2 was homologous to CTLs from other animals with the identities ranging from 33% to 40%. It contained a canonical signal peptide at the N-terminus, a low density lipoprotein receptor class A (LDLa), a C1r/C1s/Uegf/bone morphogenetic protein 1 (CUB), and a CRD with two motif Glu-Pro-Asn (EPN) and Trp-Asn-Asp (WND) in Ca2+ binding site 2...
May 14, 2018: Fish & Shellfish Immunology
Andrea Angelo Pierluigi Tripodi, Szilárd Tóth, Kata Nóra Enyedi, Gitta Schlosser, Gergely Szakács, Gábor Mező
Cyclic NGR peptides as homing devices are good candidates for the development of drug conjugates for targeted tumor therapy. In our previous study we reported that the Dau=Aoa-GFLGK(c[KNGRE]-GG-)-NH2 conjugate has a significant antitumor activity against both CD13+ HT-1080 human fibrosarcoma and CD13- but integrin positive HT-29 human colon adenocarcinoma cells. However, it seems that the free ε-amino group of Lys in the cycle is not necessary for the biological activity. Therefore, we developed novel cyclic NGR peptide-daunomycin conjugates in which Lys was replaced by different amino acids (Ala, Leu, Nle, Pro, Ser)...
2018: Beilstein Journal of Organic Chemistry
Małgorzata Sobocińska, Artur Giełdoń, Jakub Fichna, Elżbieta Kamysz
Enkephalins are involved in a number of physiological processes. However, these peptides are quickly degraded by peptidases, e.g. the neutral endopeptidase (NEP). Inhibition of the enzymatic degradation of enkephalins is one of the possible approaches to prolong their activity. Selective inhibitor of NEP, sialorphin, is the attractive lead compound for enkephalins degradation studies. In this work, an alanine scan of sialorphin and a series of its hybrids with opiorphin, synthesised by the solid phase method, were performed...
May 12, 2018: Amino Acids
Nikolai Lebedev, Igor Griva, Anders Blom, Leonard M Tender
Protein molecular conductance has attracted attention from researchers for the possibility of constructing innovative flexible biocompatible nanoscale electronic devices and smart hybrid materials. Due to protein complexity, most evaluations of protein conductivity are based on the simple estimation of protein's molecular orbital energy levels and spatial distributions without analysing its protein interaction with electrodes and the calculation of the rates of electron transfer (ET). In the present work, we included in our density functional theory (DFT) analysis an approach based on the non-equilibrium Green's function (NEGF) allowing for calculation from the first principles the molecular interaction with electrodes and thus the role of electrode materials, Fermi level, the thermal distribution of electronic energy levels, and the coupling efficiency between the molecule and the electrodes...
May 11, 2018: Physical Chemistry Chemical Physics: PCCP
Brian M Murphy, Tarik J Ozumerzifon, Charles S Henry, Mark Cornell Manning
Deamidation of asparagine (Asn) residues is one of the most common chemical degradation pathways observed in proteins. This reaction must be understood and controlled in therapeutic drug candidates, as chemical changes can affect their efficacy and safety. The analytical tools available for detection of deamidation reaction products, such as isoaspartic acid residues, are either chromatographic or electrophoretic, and require MS detection for absolute identification of peaks. High-throughput measurement of protein degradation has typically been limited to probing the target's physical state using spectroscopic techniques...
May 1, 2018: Journal of Pharmaceutical and Biomedical Analysis
Tian Zhao, Zhipeng Li, Zhouliang Guo, Ali Wang, Zhenxing Liu, Qing Zhao, Yuyin Li, Edward A McKenzie, Aipo Diao
Legumain (LGMN) is a lysosomal protease that can specifically hydrolyze proteins after carboxyl-terminal asparagine residues. It has been reported that Legumain is highly expressed in many human tumors and promotes the migratory and invasive activity of cancer cells. Due to the limitation of an abundant and affordable source of endogenous active Legumain for further function studies, we produced the recombinant protein in Pichia pastoris. The pPICZα-LGMN expression plasmid was constructed and transformed into Pichia pastoris strain and positive recombinants were identified...
May 7, 2018: Protein Expression and Purification
Christian Toonstra, Lisa Wu, Chao Li, Denong Wang, Lai-Xi Wang
High mannose type N-glycans are an important component of neutralizing epitopes on HIV-1 envelope glycoprotein gp120. They also serve as signals for protein folding, trafficking, and degradation in protein quality control. A number of lectins and antibodies recognize high-mannose type N-glycans, and glycan array technology has provided an avenue to probing these oligomannose-specific proteins. We describe in this paper a top-down chemoenzymatic approach to synthesizing a library of high-mannose N-glycans and related neoglycoproteins for glycan microarray analysis...
May 8, 2018: Bioconjugate Chemistry
Mengfei Ho, Amel Mettouchi, Brenda A Wilson, Emmanuel Lemichez
Alterations of the cellular proteome over time due to spontaneous or toxin-mediated enzymatic deamidation of glutamine (Gln) and asparagine (Asn) residues contribute to bacterial infection and might represent a source of aging-related diseases. Here, we put into perspective what is known about the mode of action of the CNF1 toxin from pathogenic E. coli, a paradigm of bacterial deamidases that activate Rho GTPases, to illustrate the importance of determining whether exposure to these factors are risk factors in the etiology age-related diseases, such as cancer...
May 3, 2018: Pathogens and Disease
Christopher J Holmes, Allen W Barton, James MacKillop, Adriana Galván, Max M Owens, Michael J McCormick, Tianyi Yu, Steven R H Beach, Gene H Brody, Lawrence H Sweet
BACKGROUND: Supportive parenting during childhood has been associated with many positive developmental outcomes for offspring in adulthood, including fewer health-risk behaviors. Little is known about the neural mechanisms underlying these associations. METHODS: The present study followed rural African Americans (n = 91, 52% female) from late childhood (11-13 years of age) to emerging adulthood (25 years of age). Parent-child communication was assessed at 11, 12, and 13 years of age...
March 20, 2018: Biological Psychiatry
Jungmi Lee, Annie Agnes Suganya Samson, Joon Myong Song
Amyloid-β (Aβ) is generated by proteolytic processing of amyloid precursor protein (APP) by beta-secretase (BACE-1) and gamma-secretase. Amyloid-β is responsible for the formation of senile plaques in Alzheimer's disease (AD). Consequently, inhibition of β-secretase (BACE-1), a rate-limiting enzyme in the production of Aβ, constitutes an attractive therapeutic approach to the treatment of AD. This paper reports an inkjet printing-based fluorescence assay for high throughput screening of β-secretase inhibitors achieved by employing a BACE-1 FRET substrate (Rh-Glu-Val-Asn-Leu-Asp-Ala-Glu-Phe-Lys-Quencher)...
August 31, 2018: Analytica Chimica Acta
Guangxu Zhu, Huayun Xiao, Qingjun Guo, Zhongyi Zhang, Jingjing Zhao, Dan Yang
Cadmium, a high toxic heavy metal, is one of the most serious contaminants in soil and a potential threat to plant growth and human health. Amino acid metabolism has the central role in heavy metal stress resistance of plants. In this paper, a pot experiment was carried out to study the effects of different concentrations of cadmium (0, 3, 6, 12, 30 mg kg-1 ) on the growth, Cd accumulation and amino acid metabolism in two Compositae plants (Ageratum conyzoides L. and Crassocephalum crepidioides). The results showed that under cadmium stress, C...
May 1, 2018: Ecotoxicology and Environmental Safety
Liwei Cao, Jolene K Diedrich, Yuanhui Ma, Nianshuang Wang, Matthias Pauthner, Sung-Kyu Robin Park, Claire M Delahunty, Jason S McLellan, Dennis R Burton, John R Yates, James C Paulson
N-glycans contribute to the folding, stability and functions of the proteins they decorate. They are produced by transfer of the glycan precursor to the sequon Asn-X-Thr/Ser, followed by enzymatic trimming to a high-mannose-type core and sequential addition of monosaccharides to generate complex-type and hybrid glycans. This process, mediated by the concerted action of multiple enzymes, produces a mixture of related glycoforms at each glycosite, making analysis of glycosylation difficult. To address this analytical challenge, we developed a robust semiquantitative mass spectrometry (MS)-based method that determines the degree of glycan occupancy at each glycosite and the proportion of N-glycans processed from high-mannose type to complex type...
June 2018: Nature Protocols
Shiraazkhan Abdul, Miet Peeters, Els Brouwers, Joyce J M C Malfliet, Frank W G Leebeek, Paul J Declerck, Dingeman C Rijken, Shirley Uitte de Willige
Around 70% of circulating alpha-2-antiplasmin (α2AP), the main natural plasmin inhibitor, is N-terminally cleaved between residues Pro12 and Asn13 by antiplasmin-cleaving enzyme. This converts native Met-α2AP into the more potent fibrinolysis inhibitor Asn-α2AP. The Arg6Trp (R6W) polymorphism affects the N-terminal cleavage rate of Met-α2AP in a purified system, with ~8-fold faster conversion of Met(R6)-α2AP than Met(W6)-α2AP. To date, assays to determine N-terminally intact Met-α2AP in plasma have been limited to an ELISA that only measures Met(R6)-α2AP...
2018: PloS One
Aleksandra E Olszewski, Dennis A Daniel, Deborah R Stein, Mignon I McCulloch, Sharon W Su, Daniel L Hames, Traci A Wolbrink
BACKGROUND AND OBJECTIVES: Despite the increasing prevalence of childhood kidney disease worldwide, there is a shortage of clinicians trained to provide peritoneal dialysis (PD). E-learning technologies may provide a solution to improve knowledge in PD. We describe the development of a virtual PD simulator and report the first 22 months of online usage. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The PD simulator was developed and released on OPENPediatrics in January of 2016...
May 2, 2018: Clinical Journal of the American Society of Nephrology: CJASN
Cheng-Wang Sheng, John E Casida, Kathleen A Durkin, Feng Chen, Zhao-Jun Han, Chun-Qing Zhao
BACKGROUND: Phenylpyrazole (fiprole) insecticides, including ethiprole, fipronil and flufiprole with excellent activity on rice planthoppers, are very important in Asia but resistance has developed after decades of use. The molecular mechanism of fipronil- but not ethiprole-resistance has been previously studied in rice planthoppers. In our laboratory, a small brown planthopper Laodelphax striatellus strain with ethiprole-resistance was cultured and the molecular mechanisms of ethiprole resistance and of cross-resistance among fiprole insecticides were investigated...
May 2, 2018: Pest Management Science
Anh Thi Tran, Åsne Bakke, Tore J Berg, Bjørn Gjelsvik, Ibrahimu Mdala, Kjersti Nøkleby, Anam Shakil Rai, John G Cooper, Tor Claudi, Karianne Løvaas, Geir Thue, Sverre Sandberg, Anne K Jenum
OBJECTIVE: To explore the associations between general practitioners (GPs) characteristics such as gender, specialist status, country of birth and country of graduation and the quality of care for patients with type 2 diabetes (T2DM). DESIGN: Cross-sectional survey. SETTING AND SUBJECTS: The 277 GPs provided care for 10082 patients with T2DM in Norway in 2014. The GPs characteristics were self-reported: 55% were male, 68% were specialists in General Practice, 82% born in Norway and 87% had graduated in Western Europe...
June 2018: Scandinavian Journal of Primary Health Care
Aoi Ono, Kazuyuki Hirooka, Yuki Nakano, Eri Nitta, Akira Nishiyama, Akitaka Tsujikawa
PURPOSE: Retinal ganglion cell (RGC) loss associated with thinning of the retinal nerve fiber layer without elevated intraocular pressure (IOP) occurs after the systemic administration of aldosterone. Since it is important to determine the mechanism of cell death independent of the IOP, we examined gene expression changes in the retina after the systemic administration of aldosterone. METHODS: Following subcutaneous implantation of an osmotic minipump into the mid-scapular region of rats, we administered an 80 μg/kg/day dose of aldosterone...
April 30, 2018: Japanese Journal of Ophthalmology
Zhaojun Nie, Jia Wang, Zed Rengel, Hongen Liu, Wei Gao, Peng Zhao
Zinc (Zn) deficiency remarkably depresses the protein concentration in the grain of winter wheat. Cultivar 'Pingan 8' showed lower Zn concentrations in the grain than did cultivar 'Yangao 006' after nitrogen (N) combined with Zn application. However, little is known about how amino acids are influenced by Zn combined with N application or about the differences in amino acid accumulation between the two winter wheat cultivars. A pot experiment was conducted to characterize amino acid accumulation in the low Zn-accumulating cultivar 'Pingan 8' and the high Zn-accumulating cultivar 'Yangao 006' at various growth stages (seedling, jointing, grain filling and maturity) as influenced by N and Zn supply...
April 22, 2018: Plant Physiology and Biochemistry: PPB
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