CD Data Research Articles

Molecular interaction of Sunset Yellow with whey protein: Multi-spectroscopic techniques and computational study

Sunset Yellow (SY) dye is an essential component in the food, pharmaceutical, and cosmetic, industries. Therefore, we studied its interaction with whey protein (β-lactoglobulin (β-LG)) using spectroscopic and molecular modeling techniques at pH 7.4. Intrinsic fluorescence data at three different temperatures suggested that the fluorescence intensity decreased upon the addition of SY dye. The fluorescence quenching constant (Ksv) values decreases in response to increase in temperature which signified the a static quenching mechanism was taking place between SY and β-LG. The thermodynamic data revealed that hydrophobic interaction was dominantly involved in the SY–β-LG interaction. The negative sign of standard Gibbs free energy (ΔG°) denoted that the SY-β-LG complex formed via spontaneous molecular interaction. The UV–Vis spectroscopy results showed that the absorbance of β-LG increased with increasing SY concentration because of complex formation. The far-UV CD data suggested that the secondary structure of β-LG increased in the presence of SY dye and the overall β-LG conformation changed. Molecular docking results showed the high-affinity binding (-11.27 kcal/mol) of SY with β-LG through hydrogen bonds and hydrophobic interactions. This study provides detailed information about food additive dye interactions with dairy products and shows conformational changes of dairy proteins due to interaction with dye.

Purification and characterization of recombinant FAD synthetase from Neurosporacrassa

FAD Synthetase (FADS) [EC 2.7.7.2], the second enzyme in flavin cofactor biosynthetic pathway converts FMN to FAD, plays an important role in many redox reactions. Neurospora crassa FADS (NcFADS) was cloned and overexpressed in E. coli cells. Recombinant NcFADS was purified in high yields of ∼8 mg per liter of bacterial culture using a single step glutathione sepharose affinity chromatography. SDS-PAGE and MALDI-MS revealed that NcFADS has a molecular mass of ∼31 kDa. Enzyme kinetic analysis monitored by reverse phase HPLC demonstrate a specific activity and kcat of 1356 nmol/min/mg and 0.69sec−1 respectively. Steady state kinetic analysis of NcFADS exhibited a Km of NcFADS for FMN is 2.7 μM and for MgATP−2 is 88.7 μM. Isothermal titration calorimetry experiments showed that the recombinant protein binds to the substrates with apparent Kd of 20.8 μM for FMN and 16.6 μM for MgATP−2. Biophysical characterization using intrinsic fluorescence suggests that the enzyme is in folded conformation. Far-UV CD data suggest that the backbone of the enzyme is predominantly in a helical conformation. Differential scanning calorimetry data shows that the Tm is 53 °C ± 1. This is the first report on cloning, purification and characterization of FADS from N. crassa. The specific activity of NcFADS is the highest than any of the reported FADS from any other source. The results obtained in this study is expected to pave way for intensive research aimed to understand the molecular basis for the extraordinarily high turnover rate of NcFADS.

Bimolecular interaction of zwitterionic surfactant with hen egg white lysozyme (HEWL): A biophysical study

The interaction between Hen Egg White Lysozyme (HEWL) and 3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propanesulphonate (CHAPS) was examined using biophysical techniques (spectrofluorometric, circular dichroism, and dynamic light scattering) at pH 9.0. The results obtained from multi-techniques showed that CHAPS interact with the HEWL strongly and affects protein conformations. The far-UV CD results suggest that lower as well as higher (1.0–15.0 mM) concentrations of CHAPS are inducing α-helical structure in HEWL. The near-UV CD and fluorescence data indicated that the tertiary structure of HEWL is alter in the presence of CHAPS. The ANS dye binding suggest that the exposure of HEWL tertiary structure is dependent on CHAPS concentration. As the concentrations of CHAPS is increasing the exposure of HEWL tertiary structure is also increasing and maximum exposure was found at 15.0 mM of CHAPS concentrations. The hydrodynamic radii of HEWL is also increase in the presence of sub-micellar and micellar concentrations of CHAPS because the tertiary structure of HEWL is disrupted. Overall, the results suggest that CHAPS is inducing secondary structure and disrupting tertiary structure of HEWL. This study provides detailed interaction of CHAPS with HEWL at the molecular level.

Transdermal Co-Delivery of Urea and Recombinant Human Growth Hormone.

Background: Urea with super-hydrating and moisturizing properties is mainly used as an adjunctive treatment of diseases associated with dry skin. In this regard, the recombinant human growth hormone (rhGH) with rejuvenating properties is used as a base material in beauty creams. Although urea easily passes through the skin, the epidermal skin barrier restricts the passage of hGH due to its size.Objective: in this research, in order to solve this problem, hydroxy propyl-beta cyclodextrin (HP-β-CD) is used as a soluble chemical enhancer.Material and Methods: UV and circular dichroism spectroscopy were used for the investigation of structural modification. The permeation process was studied in vitro on rat skin using vertical Franz diffusion cells. Enzyme-linked immunosorbent assay were used for rhGH activity assessment and evaluation of transdermal delivery.Results: First, due to the denaturing effects of urea on proteins its concentration was optimized to maintain biological structure and protein activity. UV spectroscopy and CD data proved that the secondary structure of rhGH is preserved in the presence of urea (0.5-2 M) and HP-β-CD, which elevates urea and rhGH permeation. Maximum permeability was observed at 120 min after sampling (1424.35 ng.ml.cm-2), which was much higher than the control. Using a higher concentration of urea in the formulation will significantly decrease the level of rhGH delivery.Conclusion: According to results, this strategy can be considered as a successful method for enhanced Co-delivery of rhGH and urea.

Dibenzocyclooctadiene lignans from the root bark of Schisandra sphenanthera

• Two new dibenzocyclooctadiene lignans were obtained from the root bark of Schisandra sphenanthera . • The structures were elucidated by NMR, MS, IR and CD data analysis. • Nine compounds showed cytotoxic activities with IC 50 values ranging from 13.5 to 48.8 μM. Two new dibenzocyclooctadiene lignans, schisphenlignan M and N ( 1 and 2 ), together with nine known analogues, schisantherin B ( 3 ), gomisin G ( 4 ), schisantherin D ( 5 ), schisantherin A ( 6 ), epigomisin O ( 7 ), gomisin O ( 8 ), (+)-gomisin K3 ( 9 ), schisanhenol B ( 10 ) and gomisin A ( 11 ) were isolated from the 80 % ethanol extract of root bark of Schisandra sphenanthera . Their structures were determined on the basis of spectroscopic analysis including IR, HR-ESI-MS, 1D and 2D NMR and CD spectra data. Compounds 1 - 11 were evaluated for their cytotoxic activity against human lung cancer cell line A549, and human colon cancer cell lines HTC116 and SW620, and the results showed that all of the lignans, except 3 and 8 (>50 μM), exhibited cytotoxic activities with IC 50 values ranging from 13.5 to 48.8 μM.

Anti-Inflammatory Azaphilones from the Edible Alga-Derived Fungus Penicillium sclerotiorum.

To discover the new medical entity from edible marine algae, our continuously natural product investigation focused on endophytes from marine macroalgae Grateloupia sp. Two new azaphilones, 8a-epi-hypocrellone A (1), 8a-epi-eupenicilazaphilone C (2), together with five known azaphilones, hypocrellone A (3), eupenicilazaphilone C (4), ((1E,3E)-3,5-dimethylhepta-1,3-dien-1-yl)-2,4-dihydroxy-3-methylbenzaldehyde (5), sclerotiorin (6), and isochromophilone IV (7) were isolated from the alga-derived fungus Penicillium sclerotiorum. The structures of isolated azaphilones (1–7) were elucidated by spectrometric identification, especially HRESIMS, CD, and NMR data analyses. Concerning bioactivity, cytotoxic, anti-inflammatory, and anti-fibrosis activities of those isolates were evaluated. As a result, compound 1 showed selective toxicity toward neuroblastoma cell line SH-SY5Y among seven cancer and one fibroblast cell lines. 20 μM of compounds 1, 3, and 7 inhibited the TNF-α-induced NFκB phosphorylation but did not change the NFκB activity. Compounds 2 and 6 respectively promoted and inhibited SMAD-mediated transcriptional activities stimulated by TGF-β.

Lignans with (N, N-diethyl)methyl amino group from Buxus rugulosa.

Buxrugulosides A-E, four lignan glycosides (1-4) and a protocatechuate derivative (5) featuring a rare (N, N-diethyl)methyl amino group at aromatic rings, were obtained from the aerial parts of Buxus rugulosa, which is famous for treating coronary heart disease. Their structures including absolute configurations were elucidated by HRMS, 1D and 2D NMR, and by comparing their CD data with previous reports. Compound 1 was a rare sesquilignan, and all of these compounds were the first example of lignans with (N, N-diethyl)methyl amino group.

Structural Properties of Human Chorionic Gonadotropin (hCG) Affected by Ultrasonic Irradiation: An in Vitro Study

Human chorionic gonadotropin (hCG) is a glycoprotein hormone that is an essential biomarker in oncology and pregnancy. The objective of this research was to examine the effect of ultrasonic irradiation (40 kHz) in various times of exposure (10 to 60 min) on the structure of hCG. The UV-Visible and near-UV CD data illustrated that ultrasonic irradiation could induce alterations in the tertiary structure of hCG and these conformational variations were irreversible. The ultrasonic-induced variations were observed in the intrinsic fluorescence emission. Furthermore, after long periods of exposure, ANS affinity to hCG incremented considerably. A transition to the random coil was observed in far-UV CD data. Ultrasonic irradiation could increment the negative surface charge on hCG. The effect of ultrasonic time revealed initial increment and eventual reduction in hCG size. After 60 min exposure, some new bands were observed at the SDS-PAGE profile of hCG. Collectively, our in vitro experiments demonstrated the sensitive balance between various noncovalent interactions in the structure of hCG could be easily disrupted after ultrasonic treatments. Results from this study are useful to achieve a better understanding of the ultrasonic irradiation physicochemical effects on proteins. Besides, can help to determine safe limits for people particularly, pregnant women.

Atropisomeric Properties of 9-Methyl-1,4-benzodiazepin-2-ones

AbstractThe atropisomeric and conformational properties of 1,4-benzodiazepin-2-ones were investigated by freezing the conformation with a methyl group at the C9 of 1,4-benzodiazepine. It was revealed that 1,4-benzodiazepin-2-ones exist only as a pair of enantiomers [(a1 R, a2 S) and (a1 S, a2 R)], which was confirmed by X-ray analysis. The absolute configuration of each atropisomer was deduced by comparing the [α]D and CD data with those of (–)-N-methoxycarbonylmethylated 9-methyl-5-phenyl-1,4-benzodiaepin-2-one derivative. It was elucidated that the corresponding N-methylated derivative showed similar CD spectra, although the rotational direction of [α]D was opposite to that of others.

Structural and ATPase activity analysis of nucleotide binding domain of Rv3870 enzyme of M. tuberculosis ESX-1 system

The EccC enzyme of ESX-1 system contains (i) a membrane bound Rv3870 with single ATPase domain and (ii) a cytoplasmic Rv3871 with two ATPase domains and involved in secretion of ESAT6/CFP10 factor out of the cell. In current study, we have structurally and biochemically characterized the ATPase domain (442–747 residues) of Rv3870 enzyme. The ΔRv3870 eluted as oligomer (~813 kDa) from Superdex 200 (16/60) column, as identified based on molecular mass standard and dynamics light scattering. The SAXS analysis yielded a tetrameric ring envelope of ΔRv3870, quite consistent to dynamic light scattering data. The ΔRv3870 exhibited ATPase activity having kinetic parameters, Km ~ 100 ± 40 μM, kcat ~ 1.81 ± 0.27 min−1 and Vmax ~ 54.41 μM/min/mg. ATPase activity using nine ΔRv3870 mutants showed 70–91% decrease in catalytic efficiency of the enzyme. ΔRv3870 binds Rv3871 with KD ~ 484.0 ± 10.3 nM and its catalytic efficiency is enhanced ~6.7-fold in presence of Rv3871. CD data revealed the high TM ~ 82.2 ± 0.5 °C for ΔRv3870 and enhanced in presence of ATP + Mg2+, as observed in dynamics simulation on ΔRv3870 hexameric models. Overall, our structural and biochemical studies on ΔRv3870 have explained the mechanism, which will contribute in development of antivirulence inhibitors against M. tuberculosis.

The Chagas disease study landscape: A systematic review of clinical and observational antiparasitic treatment studies to assess the potential for establishing an individual participant-level data platform.

BackgroundChagas disease (CD), caused by the parasite Trypanosoma cruzi, affects ~6–7 million people worldwide. Significant limitations still exist in our understanding of CD. Harnessing individual participant data (IPD) from studies could support more in-depth analyses to address the many outstanding research questions. This systematic review aims to describe the characteristics and treatment practices of clinical studies in CD and assess the breadth and availability of research data for the potential establishment of a data-sharing platform.Methodology/Principal findingsThis review includes prospective CD clinical studies published after 1997 with patients receiving a trypanocidal treatment. The following electronic databases and clinical trial registry platforms were searched: Cochrane Library, PubMed, Embase, LILACS, Scielo, Clintrials.gov, and WHO ICTRP.Of the 11,966 unique citations screened, 109 (0.9%) studies (31 observational and 78 interventional) representing 23,116 patients were included. Diagnosis for patient enrolment required 1 positive test result in 5 (4.6%) studies (2 used molecular method, 1 used molecular and serology, 2 used serology and parasitological methods), 2 in 60 (55.0%), 3 in 14 (12.8%) and 4 or more in 4 (3.7%) studies. A description of treatment regimen was available for 19,199 (83.1%) patients, of whom 14,605 (76.1%) received an active treatment and 4,594 (23.9%) were assigned to a placebo/no-treatment. Of the 14,605 patients who received an active treatment, benznidazole was administered in 12,467 (85.4%), nifurtimox in 825 (5.6%), itraconazole in 284 (1.9%), allopurinol in 251 (1.7%) and other drugs in 286 (1.9%). Assessment of efficacy varied largely and was based primarily on biological outcome; parasitological efficacy relied on serology in 67/85 (78.8%) studies, molecular methods in 52/85 (61.2%), parasitological in 34/85 (40.0%), microscopy in 3/85 (3.5%) and immunohistochemistry in 1/85 (1.2%). The median time at which parasitological assessment was carried out was 79 days [interquartile range (IQR): 30–180] for the first assessment, 180 days [IQR: 60–500] for second, and 270 days [IQR: 18–545] for the third assessment.Conclusions/SignificanceThis review demonstrates the heterogeneity of clinical practice in CD treatment and in the conduct of clinical studies. The sheer volume of potential IPD identified demonstrates the potential for development of an IPD platform for CD and that such efforts would enable in-depth analyses to optimise the limited pharmacopoeia of CD and inform prospective data collection.

Sesquiterpenoids and flavonoids from Pteris multifida Poir.

Phytochemical research of Pteris multifida Poir. led to the isolation of fifteen compounds, including six flavonoids (1–6) and nine sesquiterpenoids (7–15). Their structures were characterized by NMR, MS, ORD and CD data. Compounds kaempferol 3-O-α-L-rhamnoside-7-O-β-D-glucoside (1), myricetin 3-O-β-D-glucoside (2), kaempferol 3-O-β-D-glucoside (4), luteolin-7-O-β-D-rutinoside (5), quercetin-3-O-α-L-rhamnopyranoside (6), (2S,3S)-12-hydroxypterosin Q (7), (2S,3S)-pterosin Q (8), 2-hydroxypterosin C (9) and (2S)-12-hydroxypterosin A (10) were first isolated from P. multifida, and compounds 1–2 and 10 were first isolated from the family Pteridaceae. Furthermore, the chemotaxonomic significance of the isolates was discussed.

Saponins from the rhizomes of Polygonatum nodosum Hua and their chemotaxonomic significance

Phytochemical investigation on the rhizomes of Polygonatum nodosum Hua resulted in the isolation of thirteen saponins, which could be subdivided into eleven spirostanol saponins (1–5, 7–11 and 13) and two triterpenoid saponins (6 and 12). Structure elucidation of these isolates was performed based on MS, CD, 1D and 2D NMR data. All compounds (1–13) were first reported from P. nodosumthis, and compound diosgenin 3-O-α-L-rhamnopyranosyl-(1→2)-[O-α-L-arabinofuranosyl-(1 → 4)]-β-D-glucopyranoside (7) was first reported from the family Asparagaceae. Moreover, the chemotaxonomic significance of isolates was detailedly introduced.

A study of drag reduction with textile roughness on a cyclist model

Efforts were made to examine the effect of textile roughness for the reduction of aerodynamic drag experienced on a cyclist model. First of all, flow visualization experiments were conducted in a water channel with a 1/5 scale cyclist model to identify the flow separation lines on the contoured surface. Subsequently, based on the information learned, the idea of delaying flow separation on the model surface was implemented by means of sport suits. Seven sport suits featuring different textile materials and local roughness patterns were tested on a full-scale cyclist model in wind tunnel experiments, in addition to a reference case without a sport suit. From the CD data deduced, we identified a critical condition in most of the cases studied, featuring a least drag coefficient occurred at a Reynolds number within the flow speed range studied. For the best case found, the drag coefficient is amounted 7.5% less than that of the reference case at the same Reynolds number. Furthermore, the Cp and Cprms values reduced from the pressure measurements on the cyclist model with the sport suits unveil a trend that the reduction of drag actually infers the retreat of the local flow separation lines toward the rear side of the body accompanied with less severe the flow unsteadiness.

Carbazole alkaloids with potential cytotoxic activities targeted on PCK2 protein from Murraya microphylla

From the 95% aqueous ethanol extract of Murraya microphylla, five pairs of new carbazole alkaloid enantiomers, (+/–)-microphylines N–R (1a/1b–5a/5b), were isolated, together with 20 known carbazole alkaloids. The structures of the new compounds were determined by the HRMS and NMR spectroscopic data, along with the calculated electronic circular dichroism (ECD) and Mo2(AcO)4-induced CD data. The known compound (+)-mahanine (21) showed significant cytotoxicities against Du145, HepG2, HeLa, and HCT-116 cell lines, and its possible mechanism was deduced to target on phosphoenolpyruvate carboxykinase 2 (PCK2) protein via surface plasmon resonance (SPR) and molecular docking.

Ca2+ as activator of pseudoperoxidase activity of pigeon, Eurasian woodcock and chicken myoglobins: New features for meat preservation studies

Myoglobin (Mb), hemeprotein that binds dioxygen in muscle, affects meat colour. Moreover, in presence of peroxides, metMb is a potent oxidant involved in oxidative rancidity in meat. Here, following pigeon Mb purification and primary structure mass spectroscopy characterization, we determined its autoxidation rate and pseudoperoxidase activity with respect to chicken and E. woodcock Mbs. The three Mbs exhibit different autoxidation rates (0.153-h−1 pigeon, 0.194-h−1 chicken and 0.220-h−1 E. woodcock Mbs) and similar specificity constant (9.86x103 M−1s−1 pigeon, 8.81x103 M−1s−1 chicken and 9.90x103 M−1s−1 E. woodcock Mbs), considering their pseudoperoxidase activity. Moreover, for the first time, we detected an increase in pseudoperoxidase activity in presence of Ca2+, particularly at pH 5.8. NMR and CD data indicate that the nonspecific Ca2+ binding induces small local structural rearrangements that in turn slightly reduce pigeon Mb thermal stability. However, considering Ca2+ concentration variations before and post-mortem, this finding must be considered for meat preservation.

One and multi-compartments toxico-kinetic modeling to understand metals' organotropism and fate in Gammarus fossarum.

The use of freshwater invertebrates for biomonitoring has been increasing for several decades, but little is known about relations between external exposure concentration of metals and their biodistribution among different tissues. One and multi-compartments toxicokinetic (TK) models are powerful tools to formalize and predict how a contaminant is bioaccumulated. The aim of this study is to develop modeling approaches to improve knowledge on dynamic of accumulation and fate of Cd and Hg in gammarid's organs. Gammarids were exposed to dissolved metals (11.1±1.2µg.L-1 of Cd or 0.27±0.13µg.L-1 of Hg) before a depuration phase. At each sampling days, their organs (caeca, cephalon, intestine and remaining tissues) were separated by dissection before analyses. Results allowed us to determine that i) G.fossarum takes up Cd as efficiently as the mussel M.galloprovincialis, but eliminates it more rapidly, ii) organs which accumulate and depurate the most, in terms of concentrations, are caeca and intestine for both metals; iii) the one-compartment TK models is the most relevant for Hg, while the multi-compartments TK model allows a better fit to Cd data, demonstrating dynamic transfer of Cd among organs.

Palitantin derivatives from the Antarctic fungus Geomyces sp. 3-1

Two new polyketides, palitantins B and C (1 and 2), along with one known related compound (+)-palitantin (3) were obtained from the culture of the Antarctic fungus Geomyces sp. 3-1. The structures of the new compounds were elucidated by detailed analysis of HRESIMS, NMR, CD, and ECD data. Compound 3 showed potent PTP1B inhibitory activity with an IC50 value of 7.9 μM (ursolic acid as positive control, IC50 = 8.3 μM).

SHOCKWAVE STUDY ON THE WINGS NACA 0012, NACA 64 - 206, AND NASA SC (2) - 0706 WITH Λ = 15O AT 0.85 MACH NUMBER

Airfoil is used as a basic form on aircraft wings. Airfoil on the wing of the aircraft is used to produce lift that will lift the fuselage into the air. Lifting force results from the difference in pressure between the upper surface and the lower surface of an aircraft wings. In high speed flights shockwave will occur at certain parts of the wing which will adversely affect the aerodynamic performance of the wing. Wing aerodynamic performance at high speeds can be improved in various ways, one of which is by giving a angle to the wing span called a swept angle. This study will use 3D CFD simulation methods using Ansys Fluent. The airfoil used are NACA 0012, NACA 64-206, and NASA SC (2) -0706 with a chord length of 1 m, AR = 5, and λ = 1 with backward swept angle Λ = 15 °. Free stream flow is air flowing with Mach Number = 0,85 at sea level and steady conditions. Based on the simulation results, shock occurs on the upper and lower surfaces for NACA 0012 with Cl = 0 due to symmetric airfoil, whereas shock occurs only on the upper surface for NACA 64-206 and NASA SC (2) - 0706 with a Cl / Cd value of 18.55 ( NACA 64-206) and 20.78 (NASA SC (2) - 0706). This simulation also provides a visual representation of Mach Number contour plots in the middle stretch (Midspan) of the wing and Cl and Cd data.

Evaluating the adsorption of Shanghai silty clay to Cd(II), Pb(II), As(V), and Cr(VI): kinetic, equilibrium, and thermodynamic studies.

The adsorption properties of Shanghai silty clay (SSC) towards heavy metal ions Cd(II), Pb(II), As(V), and Cr(VI) were investigated by batch experiments. The effects of solid-solution ratio, pH, temperature, reaction time, and metal concentration on sorption were analyzed. In order to better understand the adsorption mechanisms, X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray fluorescence (XRF) were used to analyze the soil specimen before and after sorption. Three adsorption kinetic models and three adsorption isotherm models were used to analyze the adsorption characteristics. Thermodynamic parameters including changes in the Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) were also calculated. Sorption capacity of SSC was compared with other clay minerals reported in the literatures. The results show that the selectivity sequence is Pb(II) > Cd(II) > As(V) > Cr(VI), with equilibrium sorption capacities of 26.46, 8.90, 2.80, and 1.85mgg-1, respectively. Adsorption is largely effective on the clay surface rather than on the crystals. The clay surface turns to be flat and slippery after adsorption. The Langmuir model shows the best fit for Cd(II) and Pb(II) data, while Freundlich model is more suitable for As(V) and Cr(VI). The optimum solid-solution ratios for sorption of Cd(II), Pb(II), As(V), and Cr(VI) are 15, 6, 40, and 40g L-1, respectively. The optimum pHs for Cd(II), Pb(II), As(V), and Cr(VI) adsorption are 9.0, 6.0, 7.0, and 2.0, respectively. The pseudo-second-order kinetic is found to be the dominant sorption mechanism of these four ions on SSC. For Cd(II) and Pb(II), both particle diffusion and film diffusion are rate-limiting factors, whereas for As(V) and Cr(VI), intraparticle diffusion is the rate-controlling factor. The thermodynamic analysis reveals that the adsorption of Cd(II) and Pb(II) is spontaneous and endothermic and the system disorder increases, while adsorption of As(V) and Cr(VI) is exothermic and the system disorder decreases. Compared with most clay minerals, natural SSC exhibits comparable adsorption capacity and thus can potentially be used as a landfill liner material to retard the migration of heavy metals.