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https://www.readbyqxmd.com/read/28811554/a-new-method-to-investigate-the-catalytic-mechanism-of-yhde-pyrophosphatase-by-using-a-pyrophosphate-fluorescence-probe
#1
Qingya Shen, Hongwei Tan, Guo-Wen Xing, Jimin Zheng, Zongchao Jia
YhdE is a Maf (multicopy associated filamentation) proteins from Escherichia coli which exhibits pyrophosphatase activity towards selected nucleotides, although its catalytic mechanism remains unclear. Herein we used a novel fluorescence probe (4-isoACBA-Zn(II) complex) to characterize the enzymatic properties of YhdE and its mutant, establishing a new method for assaying pyrophosphatase catalytic function. Our results reveal for the first time that the new fluorescence sensor confers high sensitivity and specificity and pyrophosphate (PPi) is the direct catalytic product of YhdE...
August 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28811208/macromolecular-crowding-induces-molten-globule-state-in-the-native-myoglobin-at-physiological-ph
#2
Khalida Nasreen, Shahzaib Ahamad, Faizan Ahmad, Md Imtaiyaz Hassan, Asimul Islam
Here, we report the formation of molten globule state of the native myoglobin in crowded environment. We have used Soret absorption spectroscopy and far-UV circular dichroism to monitor changes in tertiary and secondary structures of myoglobin, respectively. Our results reveal that in the presence of ficoll 70, the secondary structure of myoglobin remains unchanged while tertiary structure is lost significantly. 1-anilinonaphthalene-8-sulfonate binding experiments showed that myoglobin in the presence of various concentrations of ficoll 70, has newly exposed hydrophobic surfaces...
August 12, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28801050/electron-transfer-through-arsenite-oxidase-insights-into-rieske-interaction-with-cytochrome-c
#3
Cameron Watson, Dimitri Niks, Russ Hille, Marta Vieira, Barbara Schoepp-Cothenet, Alexandra T Marques, Maria João Romão, Teresa Santos-Silva, Joanne M Santini
Arsenic is a widely distributed environmental toxin whose presence in drinking water poses a threat to >140 million people worldwide. The respiratory enzyme arsenite oxidase from various bacteria catalyses the oxidation of arsenite to arsenate and is being developed as a biosensor for arsenite. The arsenite oxidase from Rhizobium sp. str. NT-26 (a member of the Alphaproteobacteria) is a heterotetramer consisting of a large catalytic subunit (AioA), which contains a molybdenum centre and a 3Fe-4S cluster, and a small subunit (AioB) containing a Rieske 2Fe-2S cluster...
August 8, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28799758/ph-sensitive-interactions-between-cellulose-nanocrystals-and-dopc-liposomes
#4
Yotam Navon, Harisoa Radavidson, Jean-Luc Putaux, Bruno Jean, Laurent Heux
The interaction of DOPC vesicles with cellulose nanocrystals (CNCs) have been investigated using several complementary techniques. Dynamic light scattering, zeta-potential, cryo-transmission electron microscopy and isothermal titration calorimetry (ITC) analyses confirmed the formation of pH-dependent CNC-liposome complexes. ITC was used to characterize the thermodynamic properties of this interaction. Positive values of enthalpy were found at pH lower than 5 where the charge sign of the constituents was opposite...
August 11, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28798234/structural-transitions-in-conserved-ordered-beclin-1-domains-essential-to-regulating-autophagy
#5
Karen Glover, Yue Li, Shreya Mukhopadhyay, Zoe Leuthner, Srinivas Chakravarthy, Christopher L Colbert, Sangita C Sinha
Beclin 1 (BECN1) is a key regulator of autophagy, a critical catabolic homeostasis pathway that involves the sequestration of cytoplasmic components by multilayered vesicles called autophagosomes, followed by lysosomal fusion and degradation. BECN1 is a core component of class III phosphatidylinositol-3-kinase complexes responsible for autophagosome nucleation. Without heterologous binding partners, BECN1 forms an antiparallel homodimer via its coiled-coil domain (CCD). However, the last 16 CCD residues, composing an overlap helix (OH), have been crystallized in two mutually exclusive states: either as part of the CCD or packed against the C-terminal lower case β-α-repeated, autophagy-specific domain (BARAD)...
August 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28795725/rational-design-of-artificial-dye-decolorizing-peroxidases-using-myoglobin-by-engineering-tyr-trp-in-the-heme-center
#6
Le-Le Li, Hong Yuan, Fei Liao, Bo He, Shu-Qin Gao, Ge-Bo Wen, Xiangshi Tan, Ying-Wu Lin
The rational design of metalloenzymes provides advantages not only for illustrating the structure and function relationship of native enzymes, but also for creating functional artificial enzymes comparable to native enzymes. Dye-decolorizing peroxidases (DyPs) are a new family of heme peroxidases and have received much attention recently. Inspired by the structural features of native DyPs with multiple Tyr and Trp residues, we herein aimed to design functional artificial DyPs using myoglobin (Mb), an O2 carrier as a protein scaffold, by further introduction of Tyr/Trp into the secondary sphere of the heme center in the F43Y Mb mutant...
August 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28779851/a-tale-of-two-sites-differential-impairment-of-frequency-and-duration-mismatch-negativity-across-a-primarily-inpatient-versus-a-primarily-outpatient-site-in-schizophrenia
#7
Migyung Lee, Pejman Sehatpour, Elisa C Dias, Gail S Silipo, Joshua T Kantrowitz, Antigona M Martinez, Daniel C Javitt
Deficits in mismatch negativity (MMN) generation are among the best replicated neurophysiological deficits in schizophrenia, with reduced amplitude reflecting impaired information processing at the level of supratemporal auditory cortex. Differential patterns of MMN dysfunction according to deviant types have been reported across studies, with some research groups showing impairment in duration MMN but not frequency MMN, and other research groups reporting both findings. We evaluate the hypothesis that recruitment setting, reflecting current functional status, might be an important determinant of the pattern of MMN dysfunction...
August 2, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/28768117/cationic-surfactant-mediated-fibrillogenesis-in-bovine-liver-catalase-a-biophysical-approach
#8
MohsinVahid Khan, Masihuz Zaman, TajalliIlm Chandel, Mohammad Khursheed Siddiqui, Mohd Rehan Ajmal, Ali Saber Abdelhameed, RizwanHasan Khan
Protein aggregation into oligomers and mature fibrils are associated with more than 20 diseases in humans. The interactions between cationic surfactants dodecyltrimethylammonium bromide (DTAB) andtetradecyltrimethylammonium bromide (TTAB) with varying alkyl chain lengths and bovine liver catalase (BLC) were examined by various biophysical approaches. The delicate coordination of electrostatic and hydrophobic interactions with protein, play imperative role in aggregation. In this article we have reconnoitered the relation between charge, hydrophobicity and cationic surfactants DTAB and TTAB on BLC at pH 7...
August 2, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28766643/the-inter-micellar-interaction-enthalpies-of-dtab-tx100-mixed-micelles-and-their-structural-transitions
#9
Handi Yin, Peizhu Zheng, Jihua Zhao, Weiguo Shen
The heats of mixing for a series of DTAB/TX100 mixed surfactant aqueous solutions were measured by flow-mixing calorimetry and isothermal titration calorimetry (ITC) at 298.15 K and 85 kPa, which were used to calculate the inter-micellar interaction enthalpies (-ΔHC). The signs of -ΔHC for pure DTAB and TX100 micellar systems were contrary to the inter-micellar interaction parameters reported for the same systems in the literature, suggesting that these interaction parameters might have a Gibbs free energy character dominated by entropy changes...
August 2, 2017: Soft Matter
https://www.readbyqxmd.com/read/28763009/metal-binding-properties-of-the-n-terminus-of-the-functional-amyloid-orb2
#10
Thalia H Bajakian, Silvia A Cervantes, Maria A Soria, Maïwenn Beaugrand, Ji Yun Kim, Rachel J Service, Ansgar B Siemer
The cytoplasmic polyadenylation element binding protein (CPEB) homologue Orb2 is a functional amyloid that plays a key regulatory role for long-term memory in Drosophila. Orb2 has a glutamine, histidine-rich (Q/H-rich) domain that resembles the Q/H-rich, metal binding domain of the Hpn-like protein (Hpnl) found in Helicobacter pylori. In the present study, we used chromatography and isothermal titration calorimetry (ITC) to show that the Q/H-rich domain of Orb2 binds Ni(2+) and other transition metals ions with μM affinity...
August 1, 2017: Biomolecules
https://www.readbyqxmd.com/read/28754626/in-sights-into-the-effect-of-heavy-metal-stress-on-the-endogenous-mustard-cystatin
#11
Shumaila Khan, Nafees A Khan, Bilqees Bano
Phytocystatins have been ascribed several protective roles against abiotic and biotic stress conditions. It was, therefore, thought worthwhile to document the effect of heavy metal stress on the endogenous plant cystatin. The mustard cystatin, purified from Brassica juncea (B.juncea) seeds retained its functional property of cysteine proteinase inhibition, despite exposure to high concentrations of metal ions, Cd(2+) and Ni(2+). An increase in inhibitory activity, ∼26% for Ni(2+) and ∼16% for Cd(2+) was observed, suggesting changes in protein conformation upon metal ion interaction...
July 25, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28754562/molecular-investigation-on-the-binding-of-cd-ii-by-the-binary-mixtures-of-montmorillonite-with-two-bacterial-species
#12
Huihui Du, ChenChen Qu, Jing Liu, Wenli Chen, Peng Cai, Zhihua Shi, Xiao-Ying Yu, Qiaoyun Huang
Bacteria-phyllosilicate complexes are commonly found in natural environments and are capable of immobilizing trace metals. However, the molecular binding mechanisms of heavy metals to these complex aggregates still remain poorly understood. This study investigated Cd adsorption on Gram-positive Bacillus subtilis, Gram-negative Pseudomonas putida and their binary mixtures with montmorillonite using surface complexation model, Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and isothermal titration calorimetry (ITC)...
July 25, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28741466/binding-of-cxcr4-transmembrane-peptides-to-the-bacterial-chaperonin-groel
#13
Xiaoqiang Wang, Haixia Chi, Shixin Li, Yan Xu
: Newly translated membrane protein CXCR4 was observed to gain significant folding enhancement upon interacting with the bacterial chaperonin GroEL-GroES. The main fold of CXCR4 consists of 7 transmembrane α-helices distinct from soluble proteins that have dominated research on the chaperonin-assisted folding. This work extends our previous observation to the binding of GroEL with CXCR4 transmembrane peptides, which are mainly composed of hydrophobic residues characteristic of the substrates recognized by the chaperonin...
July 24, 2017: Protein and Peptide Letters
https://www.readbyqxmd.com/read/28735008/trehalose-induced-structural-modulation-of-bovine-serum-albumin-at-ambient-temperature
#14
Ahana Das, Pijush Basak, Rudradip Pattanayak, Turban Kar, Rajib Majumder, Debadrita Pal, Anindita Bhattacharya, Maitree Bhattacharyya, Samudra Prosad Banik
Trehalose is a well-known protein stabilizing osmolyte. The present study has been designed to understand the interaction of trehalose with BSA at ambient temperature. Steady state fluorescence and life-time analysis along with CD, DLS and ITC have been employed to show that trehalose causes surface-associated structural perturbation of BSA to promote its compaction. Trehalose at 0.1M concentration resulted in increased solvent exposure of one of the two tryptophans of BSA with a 5nm redshift in emission and enhanced susceptibility to acrylamide quenching with an increase in KSV from 2...
July 19, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28727856/systematic-studies-of-the-interactions-between-a-model-polyphenol-compound-and-microbial-%C3%AE-glucosidases
#15
Viviam M da Silva, Juliana A P Sato, Juscemácia N Araujo, Fabio M Squina, João R C Muniz, Karin A Riske, Wanius Garcia
Lignin is a major obstacle for cost-effective conversion of cellulose into fermentable sugars. Non-productive adsorption onto insoluble lignin fragments and interactions with soluble phenols are important inhibition mechanisms of cellulases, including β-glucosidases. Here, we examined the inhibitory effect of tannic acid (TAN), a model polyphenolic compound, on β-glucosidases from the bacterium Thermotoga petrophila (TpBGL1 and TpBGL3) and archaeon Pyrococcus furiosus (PfBGL1). The results revealed that the inhibition effects on β-glucosidases were TAN concentration-dependent...
2017: PloS One
https://www.readbyqxmd.com/read/28708944/indirect-comparison-of-bronchial-thermoplasty-versus-omalizumab-for-uncontrolled-severe-asthma
#16
Robert M Niven, Michael R Simmonds, Michael J Cangelosi, Dominic P Tilden, Suzanne Cottrell, Narinder S Shargill
OBJECTIVE: Bronchial thermoplasty (BT) as an add-on therapy for uncontrolled severe asthma is an alternative to biologic therapies like omalizumab (OM). We conducted an indirect treatment comparison (ITC) to appraise comparative effectiveness of BT and OM. METHODS: A systematic literature review identified relevant randomized controlled trials. The ITC followed accepted methodology. RESULTS: The ITC comprised a sham-controlled trial of BT (AIR2) and two placebo-controlled trials of OM (INNOVATE; EXTRA)...
July 14, 2017: Journal of Asthma: Official Journal of the Association for the Care of Asthma
https://www.readbyqxmd.com/read/28708402/two-step-micellization-model-the-case-of-long-chain-carboxylates-in-water
#17
Žiga Medoš, Marija Bešter-Rogač
The micellization behavior of the long-chain carboxylates-sodium and potassium octanoate (NaC8 and KC8), sodium decanoate (NaC10), potassium decanoate (KC10), cesium decanoate (CsC10), choline decanoate (ChC10), and sodium dodecanoate (NaC12)-in aqueous solutions were studied using isothermal titration calorimetry (ITC) in the temperature range between 288.15 and 328.15 K. Experimental data were analyzed by help of an improved model treating the micellization process as a two-step process. Furthermore, consideration of the state of the stock and titrated solutions during the experiment allowed for the elimination of all usually used empirical parameters...
July 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28705212/moringa-isothiocyanate-complexed-with-%C3%AE-cyclodextrin-a-new-perspective-in-neuroblastoma-treatment
#18
Sabrina Giacoppo, Renato Iori, Patrick Rollin, Placido Bramanti, Emanuela Mazzon
BACKGROUND: Several lines of evidence suggest the consume of natural products for cancer prevention or treatment. In particular, isothiocyanates (ITCs) exerting anti-cancer properties, have received great interest as potential chemotherapeutic agents. This study was designed to assess the anti-proliferative activities of a new preparation of Moringa oleifera-derived 4-(α-L-rhamnopyranosyloxy)benzyl ITC (moringin) complexed with alpha-cyclodextrin (moringin + α-CD; MAC) on SH-SY5Y human neuroblastoma cells...
July 14, 2017: BMC Complementary and Alternative Medicine
https://www.readbyqxmd.com/read/28702532/a-supramolecular-miktoarm-star-polymer-based-on-porphyrin-metal-complexation-in-water
#19
Zhanyao Hou, Wim Dehaen, Joël Lyskawa, Patrice Woisel, Richard Hoogenboom
A novel supramolecular miktoarm star polymer was successfully constructed in water from a pyridine end-decorated polymer (Py-PmDEGA) and a metalloporphyrin based star polymer (ZnTPP-(PEG)4) via metal-ligand coordination. The Py-PmDEGA moiety was prepared via a combination of reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequent aminolysis and Michael addition reactions to introduce the pyridine end-group. The ZnTPP(PEG)4 star-polymer was synthesized by the reaction between tetrakis(p-hydroxyphenyl)porphyrin and toluenesulfonyl-PEG, followed by insertion of a zinc ion into the porphyrin core...
July 25, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28701585/banning-tobacco-price-promotions-smoking-related-beliefs-and-behaviour-findings-from-the-international-tobacco-control-four-country-itc-4c-survey
#20
Sherine El-Toukhy, Kelvin Choi, Sara C Hitchman, Maansi Bansal-Travers, James F Thrasher, Hua-Hie Yong, Richard J O'Connor, Ce Shang
BACKGROUND: Ecological models emphasise multilevel influences on health behaviours. While studies show that exposure to price promotions is associated with smoking behaviour and its antecedents, less is known about whether these associations differ by macro-level factors such as national price promotion policies. METHODS: Current and former smokers (N=4698) from the International Tobacco Control Policy Evaluation Project four-country cohort were included in weighted multivariate logistic regression models to examine individual-level associations between exposure to price promotions at waves 7 and 8 (conducted in 2008-2009 and 2010-2011) and beliefs (social and injunctive norms, functional value of smoking, misconceptions around smoking and beliefs of tobacco industry and its regulations) and behaviour at wave 8, stratified by whether countries allow (Australia and USA) or ban (Canada and UK) price promotions...
July 12, 2017: Tobacco Control
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