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Adam Kasparek, Bogdan Smyk
The fluorescence technique is very popular and has been used in many fields of research. It is simple in its assumptions but not very easy to use. One of the main problems is the inner filter effect (IF) I and II which takes place in the cuvette. IF type I is permanently present, but IF type II occurs only when absorption and fluorescence spectra overlap. To avoid IF type I, absorbencies in the cuvette should be smaller than 0.05, which is however very difficult to obtain in many experiments. In this work we propose a new method to solve these problems in the case of a Cary Eclipse fluorimeter, having horizontally-oriented slits, based on old equations developed in the middle of the last century...
March 13, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Catarina S H Jesus, Pedro Fernandes Cruz, Luis G Arnaut, Rui M M Brito, Carlos Serpa
The understanding of fast folding dynamics of single α-helices comes mostly from studies on rationally designed peptides displaying sequences with high helical propensity. The folding/unfolding dynamics and energetics of α-helix conformations in naturally occurring peptides remains largely unexplored. Here we report the study of a protein fragment analogue of the C-peptide from bovine pancreatic ribonuclease-A, RN80, a 13-amino acid residue peptide that adopts a highly populated helical conformation in aqueous solution...
March 20, 2018: Journal of Physical Chemistry. B
Süleyman Cinar, Claus Czeslik
We compare the binding of an inhibitor with that of a natural peptide to Ca2+ saturated calmodulin (holo-CaM). As inhibitor we have chosen trifluoperazine (TFP) that is inducing a huge conformational change of holo-CaM from the open dumbbell-shaped to the closed globular conformation upon binding. On the other hand, melittin is used as model peptide, which is a well-known natural binding partner of holo-CaM. The experiments are carried out as a function of pressure to reveal the contribution of volume or packing effects to the stability of the calmodulin-ligand complexes...
March 16, 2018: Biochimica et Biophysica Acta
Haofeng Gao, Chanjuan Li, Ramesh Bandikari, Ziduo Liu, Nan Hu, Qiang Yong
BACKGROUND: In industries lipolytic reactions occur in insensitive conditions such as high temperature thus novel stout esterases with unique properties are attracts to the industrial application. Protein engineering is the tool to obtain desirable characters of enzymes. A novel esterase gene was isolated from South China Sea and subjected to a random mutagenesis and site directed mutagenesis for higher activity and thermo-stability compared to wild type. RESULTS: A novel esterase showed the highest hydrolytic activity against p-nitrophenyl acetate (pNPA, C2) and the optimal activity at 40 °C and pH 8...
March 19, 2018: Microbial Cell Factories
Aparna Prasad, Matthew A Sdano, Rena J Vanzo, Patricia A Mowery-Rushton, Moises A Serrano, Charles H Hensel, E Robert Wassman
BACKGROUND: Chromosomal microarray analysis (CMA) is recommended as the first-tier clinical diagnostic test for individuals with developmental disabilities. In addition to detecting copy number variations, CMA platforms with single nucleotide polymorphism probes can detect large homozygous regions within the genome, which represent potential risk for recessively inherited disorders. METHODS: To determine the frequency in which pathogenic or likely pathogenic variants can be detected in these regions of homozygosity, we performed whole exome sequencing (WES) in 53 individuals where homozygosity was detected by CMA...
March 20, 2018: BMC Medical Genetics
Supawadee Sukseree, Lajos László, Florian Gruber, Sophie Bergmann, Marie Sophie Narzt, Ionela Mariana Nagelreiter, Romana Höftberger, Kinga Molnár, Günther Rauter, Thomas Birngruber, Lionel Larue, Gabor G Kovacs, Erwin Tschachler, Leopold Eckhart
Defects in autophagy and the resulting deposition of protein aggregates have been implicated in aging and neurodegenerative diseases. While gene targeting in the mouse has facilitated the characterization of these processes in different types of neurons, potential roles of autophagy and accumulation of protein substrates in neuroepithelial cells have remained elusive. Here we report that Atg7f/f Tyr-Cre mice, in which autophagy-related 7 (Atg7) is conditionally deleted under the control of the tyrosinase promoter, are a model for accumulations of the autophagy adapter and substrate sequestosome-1/p62 in both neuronal and neuroepithelial cells...
March 17, 2018: Molecular Neurobiology
Vincent Normant, Thierry Mourer, Simon Labbe
In the fission yeast Schizosaccharomyces pombe , acquisition of exogenous heme is largely mediated by the cell membrane-associated Shu1. Here, we report that Str3, a member of the major facilitator superfamily of transporters promotes cellular heme import. Using a strain that cannot synthesize heme de novo ( hem1Δ ) and lacks Shu1, we found that the heme-dependent growth deficit of this strain is rescued by hemin supplementation in the presence of Str3. Microscopic analyses of a hem1Δ shu1Δ str3Δ mutant strain in the presence of the heme analog zinc mesoporphyrin IX (ZnMP) revealed that ZnMP fails to accumulate within the mutant cells...
March 16, 2018: Journal of Biological Chemistry
Márcia Trapp, Sandra Costa Valle, Alan Gomes Pöppl, Ana Lúcia Fernandes Chittó, Luiz Carlos Kucharski, Roselis Silveira Martins Da Silva
The present study determined the effect of osmotic stress on the insulin-like receptor binding characteristics and on glucose metabolism in the anterior (AG) and posterior (PG) gills of the crab Neohelice granulata. Bovine insulin increased the capacity of the PG cell membrane to phosphorylate exogenous substrate poly (Glu:Tyr 4:1) and the glucose uptake in the control crab group. The crabs were submitted to three periods of hyperosmotic (HR) and hyposmotic (HO) stress, for 24, 72 and 144 h, to investigate the insulin-like receptor phosphorylation capacity of gills...
March 13, 2018: General and Comparative Endocrinology
Zsofia Miskolczi, Michael P Smith, Emily J Rowling, Jennifer Ferguson, Jorge Barriuso, Claudia Wellbrock
Despite the general focus on an invasive and de-differentiated phenotype as main driver of cancer metastasis, in melanoma patients many metastatic lesions display a high degree of pigmentation, indicative for a differentiated phenotype. Indeed, studies in mice and fish show that melanoma cells switch to a differentiated phenotype at secondary sites, possibly because in melanoma differentiation is closely linked to proliferation through the lineage-specific transcriptional master regulator MITF. Importantly, while a lot of effort has gone into identifying factors that induce the de-differentiated/invasive phenotype, it is not well understood how the switch to the differentiated/proliferative phenotype is controlled...
March 16, 2018: Oncogene
Arnold Groehler, Stefan Kren, Qinglu Li, Maggie Robledo-Villafane, Joshua Schmidt, Mary Garry, Natalia Tretyakova
Myocardial infarction (MI) is a life-threatening condition that can occur when blood flow to the heart is interrupted due to a blockage in one or more of the coronary vessels. Current treatments of MI rapidly restore blood flow to the affected myocardium using thrombolytic agents or angioplasty. Adverse effects including inflammation, tissue necrosis, and ventricular dysfunction are, however, not uncommon following reperfusion therapy. These conditions are thought to be caused by a sudden influx of reactive oxygen species (ROS) to the affected myocardium...
March 11, 2018: Free Radical Biology & Medicine
Negin Sabziparvar, Yosra Saeedi, Mina Nouri, Atefeh Sadat Najafi Bozorgi, Elahe Alizadeh, Farnoosh Attar, Keivan Akhtari, Seyyedeh Elaheh Mousavi, Mojtaba Falahati
NPs have received a great attention in biological and medical applications due to their unique features. However, their induced adverse effects on the biological system are not well explored. Herein, the interaction of silicon dioxide nanoparticle (SiO2 NP) with human hemoglobin (Hb) and lymphocyte cell line was evaluated under physiological conditions by multi spectroscopic (intrinsic and synchronous fluorescence spectroscopy, and circular dichrosim (CD)), molecular docking, and cellular (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and acridine orange/ethidium bromide (AO/EB) staining) methods...
March 14, 2018: Journal of Physical Chemistry. B
Andrea Angeli, Fatmah A S Alasmary, Sonia Del Prete, Sameh M Osman, Zeid AlOthman, William A Donald, Clemente Capasso, Claudiu T Supuran
The activation of the δ-class carbonic anhydrase (CAs, EC from the diatom Thalassiosira weissflogii (TweCAδ) was investigated using a panel of natural and non-natural amino acids and amines. The most effective activator of TweCAδ was d-Tyr (KA of 51 nM), whereas several other amino acids and amines, such as L-His, L-Trp, d-Trp, dopamine and serotonin were submicromolar activators (KA s from 0.51 to 0.93 µM). The most ineffective activator of TweCAδ was 4-amino-l-Phe (18.9 µM), whereas d-His, l-/d-Phe, l-/d-DOPA, l-Tyr, histamine, some pyridyl-alkylamines, l-adrenaline and aminoethyl-piperazine/morpholine were moderately potent activators (KA s from 1...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
Lingdi Zhang, Hengbo Zhou, Xueni Li, Rebecca L Vartuli, Michael Rowse, Yongna Xing, Pratyaydipta Rudra, Debashis Ghosh, Rui Zhao, Heide L Ford
Eya genes encode a unique family of multifunctional proteins that serve as transcriptional co-activators and as haloacid dehalogenase-family Tyr phosphatases. Intriguingly, the N-terminal domain of Eyas, which does not share sequence similarity to any known phosphatases, contains a separable Ser/Thr phosphatase activity. Here, we demonstrate that the Ser/Thr phosphatase activity of Eya is not intrinsic, but arises from its direct interaction with the protein phosphatase 2A (PP2A)-B55α holoenzyme. Importantly, Eya3 alters the regulation of c-Myc by PP2A, increasing c-Myc stability by enabling PP2A-B55α to dephosphorylate pT58, in direct contrast to the previously described PP2A-B56α-mediated dephosphorylation of pS62 and c-Myc destabilization...
March 13, 2018: Nature Communications
Esam A Orabi, Ann M English
S-aromatic motifs are important noncovalent forces for protein stability and function but remain poorly understood. Hence, we performed quantum calculations at the MP2(full)/6-311++G(d,p) level on complexes between Cys (H2 S, MeSH) and Met (Me2 S) models with models of Phe (benzene, toluene), Trp (indole, 3-methylindole), Tyr (phenol, 4-methylphenol) and His (imidazole, 4-methylimidazole). The most stable gas-phase conformers exhibit binding energies of -2 to -6 kcal/mol and the S atom lies perpendicular to the ring plane...
March 13, 2018: Journal of Physical Chemistry. B
Xue-Ping Wang, Ya-Lan Liu, Ling-Yun Mei, Chu-Feng He, Zhi-Jie Niu, Jie Sun, Yu-Lin Zhao, Yong Feng, Hua Zhang
Mutation in the gene encoding microphthalmia-associated transcription factor (MITF) lead to Waardenburg syndrome 2 (WS2), an autosomal dominantly inherited syndrome with auditory-pigmentary abnormalities, which is clinically and genetically heterogeneous. Haploinsufficiency may be the underlying mechanism for WS2. However, the mechanisms explaining the genotypic and phenotypic variations in WS2 caused by MITF mutations are unclear. A previous study revealed that MITF interacts with LEF-1, an important factor in the Wnt signaling pathway, to regulate its own transcription through LEF-1-binding sites on the MITF promoter...
March 12, 2018: Journal of Human Genetics
Manoj Veleeparambil, Darshana Poddar, Samar Abdulkhalek, Patricia M Kessler, Michifumi Yamashita, Saurabh Chattopadhyay, Ganes C Sen
Mammalian TLRs recognize microbial infection or cell death-associated danger signals and trigger the appropriate cellular response. These responses determine the strength and the outcome of the host-microbe interaction. TLRs are transmembrane proteins located on the plasma or the endosomal membrane. Their ectodomains recognize specific microbial or endogenous ligands, and the cytoplasmic domains interact with specific proteins to activate intracellular signaling pathways. TLR9, an endosomal TLR, is activated by endocytosed DNA...
March 12, 2018: Journal of Immunology: Official Journal of the American Association of Immunologists
Eliana Marzol, Cecilia Borassi, Mauro Bringas, Ana Sede, Diana Rosa Rodríguez Garcia, Luciana Capece, Jose M Estevez
Extensins (EXTs) are highly repetitive plant O-glycoproteins that require several post-translational modifications (PTMs) to become functional in plant cell walls. First, they are hydroxylated on contiguous proline residues; then, they are O-glycosylated on hydroxyproline (Hyp) and serine. After secretion into the apoplast, O-glycosylated EXTs form a tridimensional network organized by inter- and intra-Tyr linkages. Recent studies have made significant progress in the identification of the enzymatic machinery required to process EXTs, which includes prolyl 4-hydroxylases (P4Hs), glycosyltransferases (GTs), papain-type cysteine-endopeptidases (CEPs), and peroxidases (PERs)...
March 9, 2018: Molecular Plant
Xiangrong Li, Kaiwei Wang, Yanru Peng
The interaction of nanoparticles (NPs) with proteins is a topic of high relevance for the medical application of nanomaterials. In the study, a comprehensive investigation was performed for the binding properties of silver nanoparticles (AgNPs) to pepsin. The results indicate that the binding of AgNPs to pepsin may be a static quenching mechanism. Thermodynamic analysis reveals that AgNPs binds to pepsin is synergistically driven by enthalpy and entropy, and the major driving forces are hydrophobic and electrostatic interactions...
March 9, 2018: Chemico-biological Interactions
Zhenxing Chi, Songwen Tan, Xu Tan, Lin Zhong, Weiguo Li
The pollution of heavy metals is a severer problem for the ecosystems in waters. The toxicity of Cd2+ on phycocyanin (PC) is studied in molecular level in this work. The fluorescence quenching of PC is observed by the adding Cd2+ from 0 to 500 × 10-7  mol L-1 . From the theoretical calculation and the time-resolved fluorescence decay profiles, the fluorescence quenching of PC by Cd2+ is found to be static. The synchronous fluorescence spectra are used to study the change in amino acid residues of PC molecules, indicating that the effect of Cd2+ on the Trp of PC is more significant than the Tyr...
March 11, 2018: Environmental Science and Pollution Research International
Stanley Ns Vasconcelos, Juliana M Sciani, Nicole Mambeli Lisboa, Helio A Stefani
BACKGROUND: Structural component of proteins and peptides, amino acids have been used as building blocks in the synthesis of more complex molecules with antitumor activity against several types of cancer. OBJECTIVE: The search for new anticancer compounds is ongoing, especially for cancers that are very aggressive and have poor prognoses, such as leukemia. METHOD: Here, we report a method to synthesize Tyr-Tyr dipeptides via sonochemistry reactions followed by functionalization of these Tyr-Tyr dipeptides with Suzuki-Miyaura and Sonogashira cross-coupling reactions in good yields...
March 9, 2018: Medicinal Chemistry
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