BACKGROUND:Glycation is an approach in dealing with heat-induced protein aggregation. The relationship between degree of glycation and heat-induced structural changes is still unclear. The present work investigates the effect of different numbers and sites of glycated residues on heat-induced structural changes of bovine serum albumin (BSA). Glycation of BSA was carried out with xylose (Xyl) and galactose (Gal) by Maillard reaction. Glycated residues in BSA were identified by liquid chromatography-tandem mass spectrometry, and heat-induced protein structural changes were characterized by fluorescence emission and synchronous fluorescence spectra, 8-anilino-1-naphthalenesulfonic acid fluorescence, Fourier transform infrared (FTIR) and circular dichroism (CD) spectra.RESULTS:The numbers of glycated residues were 2 and 13 when BSA was glycated by Gal (BSA - Gal) and Xyl (BSA - Xyl), respectively. There were shifts of maximum wavelengths and decreases in fluorescence intensities for both intrinsic and extrinsic fluorescences; shifts of FTIR amide I, III, and A bands; and decrease or increase of CD band intensities, α-helix and β-sheet percentages when BSA was heated. Glycation with Gal or Xyl restrained in similar degrees those changes, including fluorescence wavelengths, amide I band, CD band intensities, and α-helix and β-sheet percentages.CONCLUSION:Xyl glycated more residues than Gal, while their effects were similar in restraining heat-induced BSA structural changes. © 2017 Society of Chemical Industry.

The interaction modes and nanoparticle characteristics of bovine serum albumin (BSA) with quercetin (QUE) and anthocyanin (ACN) were comparatively investigated.The fluorescence of BSA was greatly quenched by QUE in both static (at low concentration) and dynamic (at high concentration) modes,while fluorescence quenching of BSA by ACN was just in a static mode.The binding constant of BSA with QUE was higher than that with ACN.BSA interacted with QUE and ACN by hydrophobic force and electrostatic force,respectively,to form BSA-QUE and BSA-ACN nanoparticles.The average diameters of BSA-QUE and BSA-ACN were 42.5 nm and 53.7 nm,respectively.The ξ-potentials of BSA-QUE and BSA-ACN were-25.64 and-21.50 mV,respectively.One mole of BSA could combine 8 moles of QUE or 10 moles of ACN.BSA-QUE nanoparticles were smaller and more stable than BSA-ACN nanoparticles.The DPPH and ABTS radical scavenging rates of BSA-QUE were higher than those of BSA-ACN.

运用荧光光谱、同步荧光光谱、傅里叶变换红外光谱和圆二色谱研究卵白蛋白与油酸相互作用的方式及机理.结果表明,油酸与卵白蛋白相互作用导致卵白蛋白荧光猝灭,猝灭方式由动态猝灭(未加热处理)转变为静态猝灭(加热处理),其相互作用力为疏水作用和氢键,且随着油酸浓度的增大,相互作用力增强.与油酸相互作用后,卵白蛋白酪氨酸残基和色氨酸残基的荧光光谱蓝移,α-螺旋和β-转角的含量减少,β-折叠含量增加;而无规卷曲的含量增大(油酸与卵白蛋白物质的量比为10∶1).综上所述,油酸与卵白蛋白间通过疏水作用和氢键发生相互作用,导致卵白蛋白二级结构发生变化.

乳白蛋白与油酸形成的复合物具有癌细胞生长抑制作用(Human alpha-lactalbumin made lethal to tumor cells, HAMLET).本文制备了卵白蛋白(Ovalbumin,OVA)和油酸(Oleic acid,OA)的复合物(OVA-OA),通过检测细胞生长抑制、细胞膜通透性、细胞生长周期和凋亡的变化,分析了OVA-OA对人结肠癌细胞(Caco-2)的生长抑制作用以及其中OA对生长抑制作用的贡献.结果表明,当OVA-OA中OA的浓度达到182 μmol/L时,OVA-OA对Caco-2细胞有显著(p＜0.05)生长抑制作用,273μmol/L时生长抑制作用增强,且随着作用时间的延长(1～3 h)而增强.在182 μmol/L时,OA对Caco-2细胞也有生长抑制作用,其剂量效应关系与OVA-OA一致.但当OA浓度为273 μmol/L时,其生长抑制作用弱于OVA-OA的.OVA-OA和OA均会促使乳酸脱氢酶(Lactate dehydrogenase,LDH)释放,增大晚期凋亡和坏死的细胞百分比,阻滞细胞周期在G0/G1期和S期.由此可知,OVA-OA对结肠癌细胞具有HAMLET样生长抑制作用,其中OA起主要作用.OVA-OA对人结肠癌细胞的生长抑制作用是通过损伤细胞膜、阻滞细胞生长周期和促进细胞凋亡来实现的.

Objective The characteristic fluorescence of Maillard reaction systems (MRS) of bovine serum albumin (BSA) and different monosaccharides (xylose, glucose, and galactose) and disaccharides (lactose and maltose) were investigated. Methods BSA and different sugar Maillard reaction systems were prepared in phosphate buffer saline (pH 7.4) with a molar ratio of 1:667, and heated at 50 ℃ for 7 days. The fluorescence development of the BSA and sugar MRS were assessed by 3-dimensional fluorescence and synchronous fluorescence. Results The BSA and sugar MRS exhibited the characteristic new fluorescence peaks (λex 330~340 nm, λem 400~425 nm) on 3-dimensional fluorescence spectra, and their fluorescence intensity increased with heating time. The blue shifts of the maximum emission wave lengths occurred on synchronous fluorescences (Δλ=15 nm and Δλ=60 nm). The degree of fluorescence change of both 3-dimensional and synchronous fluorescences were in accordance to the degree of Maillard reaction, in an order of BSA-Xyl>BSA-Gal>BSA-Glu, BSA-Mal, and BSA-Lac. Conclusion Both characteristic fluorescence peak and blue shift occurred during BSA and sugar Maillard reaction, which could be used as the indicators for progress of Maillard reaction and conformation change of BSA.

Garlic has been used as foods and herbal remedy, which has many biological activities such as inhi-bition of bacteria growth. Sulfur compounds are the major bioactive compounds in garlic, and also contribute to garlic pungent flavor. Alliin, precursor of these sulfur compounds, could be transformed to allicin by allinase. Allicin is very unstable and easy to be converted to other sulfur compounds. This article describes the sulfur compounds associated with garlic flavor, transformations between sulfur compounds, and biological activity of sulfur compounds. The influences of different processing technologies on sulfur compounds and garlic flavor have also been addressed, especially the processing for black garlic and associated flavor change.

Here we investigated the possible roles of oxidative stress in the formation of decreased thermotaxis to cultivation temperature in lead (Pb)-exposed nematodes Caenorhabditis elagans. Exposure to Pb at the examined concentrations decreased thermotaxis behaviors, and induced severe deficits in the structural properties of AFD sensory neurons. Meanwhile, Pb exposure caused the induction of severe oxidative damage, reactive oxygen species (ROS) production, and mitochondrial dysfunction in young adults. Moreover, pre-treatment with the antioxidants dimethyl sulfoxide (DMSO), ascorbate and N-acetyl-L-cysteine (NAC), used to inhibit both the ROS elevation and the mitochondrial dysfunction caused by Pb exposure, at the L2-larval stage prevented the induction of oxidative damage and the formation of severe deficits in thermotaxis and structural properties of AFD sensory neurons in Pb-exposed young adults. Therefore, the formation of oxidative stress caused by Pb exposure may be due to both the induction of ROS elevation and damage to mitochondrial function, and oxidative stress may play a key role in inducing the neurotoxic effects on the structures and function of AFD sensory neurons in Pb-exposed nematodes.

Objective: To investigate the association of pharyngeal pumping with mean lifespan in metal exposed nematode Caenorhabditis elegans. Methods: The metals of Hg, Pb, Cr, and Cd were selected for toxicity assay. The alterations of pharyngeal pumping in metal exposed nematodes were examined. In addition, the association of pharyngeal pumping with mean lifespan in metal exposed nematodes was determined by linear regression method. Results: Exposure to Hg and Pb at all examined concentrations and to Cr and Cd at concentrations from 100 μmol•L^(-1) to 200 μmol•L^(-1) caused a significant decrease of pumping rate. The alterations of pharyngeal pumping rate in metal exposed nematodes were significantly correlated with the concentrations of examined metals. Moreover, the pharyngeal pumping rate was significantly correlated with mean lifespan in metal exposed nematodes. Conclusion: The close association of pharyngeal pumping with mean lifespan can be observed in metal exposed nematodes, and the endpoint of lifespan can be effectively substituted by the endpoint of pumping rate while assessing the toxicity on aging from environmental toxicants.

Two heterocycle-based derivatives that can be used as two-photon absorption chromophore, 9-butyl-3-(2, 6-diphenylpyridin-4-yl)-9H-carbazole (BDPYC) and 9-butyl-3-(4-(2, 6-diphenylpyridin-4-yl)styryl)-9H-carbazole (BDPSC) have been successfully synthesized and fully characterized by elemental analysis, IR, 1H NMR, 13C NMR and MS. The molecules possess D-π-A structures, but have different π bridge. The 9-butylcarbazole is used as a donor (D), and the pyridine ring is used as an acceptor (A). One- and two-photon absorption and excited fluorescence properties in various solvents were experimentally investigated. Two-photon initiated optical data recording experiments have been carried out under 740nm laser radiation, and the possible mechanism of optical data storage is discussed based on theoretical calculations.

In nematodes, 10 J/m2/min of UV irradiation induced a mild reproductive toxicity. Pre-treatment with UV irradiation at 10 J/m2/min suppressed the formation of reproductive defects, and activated a noticeable reduction of percentage of population with hsp-16.2::gfp expression, an obvious elevation of superoxide dismutase activities, and decrease of oxidative damage in 50 and 100 μM Cd exposed nematodes; however, pre-treatment with UV irradiation at 20 J/m2/min caused a significant decrease of brood sizes or increase of generation times in Cd-exposed nematodes. Pre-treatment with mild UV irradiation did not suppress the formation of reproductive defects in 150 μM Cd-exposed nematodes. Furthermore, the adaptive response to reproductive toxicity from Cd exposure was not observed in a reactive oxygen species sensitive mev-1(kn1) mutant. Therefore, pre-treatment with mild UV irradiation triggers the resistance to reproductive toxicity from Cd exposure by at least partially inducing adaptation to oxidative stress and through a mev-1-dependent pathway.

UV irradiation at 10 J/m2/min induced a mild toxicity on locomotion behaviors and stress response in Caenorhabditis elegans. Pre-treatment with UV irradiation at 10 J/m2/min at L2-larva stage prevented the formation of locomotion behavioral defects, and activated a noticeable reduction of stress response and oxidative damage in 50 and 100 μM metal (Hg, Pb, and Cr) exposed nematodes. Pre-treatment with UV irradiation at 20 J/m2/min caused a significant decrease of locomotion behaviors in metal exposed nematodes, and pre-treatment with mild UV irradiation could not prevent the formation of locomotion behavioral defects in 200 μM metal exposed nematodes. Moreover, the adaptive response to toxicity on locomotion behaviors induced by metal exposure was not formed in mev-1 mutants. Therefore, pre-treatment to mild UV irradiation activates the cross-adaptation response to toxicity on locomotion behaviors induced by metal exposure, and this kind of adaptive response may be under the control of MEV-1 function.

Adaptive response to neurotoxicity on locomotion behavior by severe metal exposure was investigated in Caenorhabditis elegans. Exposure to 2.5μM of metals induced a moderate but significant reduction of locomotion behavior and induction of hsp-16.2::gfp expression. After pre-exposure to 2.5μM of metals, the reduced locomotion behavior induced by subsequent 50 and 100μM of metal exposure were significantly prevented, and the induction of hsp-16.2::gfp expression caused by subsequent 50 and 100μM of metal exposure were significantly suppressed. In contrast, after pre-exposure to 50μM examined metals, the reduced locomotion behavior induced by subsequent 50 and 100μM metal exposure were further decreased, and the noticeable induction of hsp-16.2::gfp expression caused by subsequent severe metal exposure were further enhanced. Therefore, pre-treatment with mild metal exposure can activate the adaptive response to neurotoxicity on locomotion behavior induced by subsequent severe metal exposure in nematodes.

Chemotaxis to water-soluble attractants is mainly controlled by ASE sensory neuron whose specification is regulated by che-1 in Caenorhabditis elegans. Our data suggested that exposure to high concentrations of metals, such as Pb, Cu, Ag, and Cr, would result in severe defects of chemotaxis to water-soluble attractants of NaCl, cAMP, and biotin. Moreover, the morphology of ASE neuron structures as observed by relative fluorescent intensities and relative size of fluorescent puncta of cell bodies, relative lengths of sensory endings in ASE neurons, and the expression patterns of che-1 were obviously altered in metal exposed animals when they meanwhile exhibited obvious chemotaxis defects to water-soluble attractants. In addition, the dendrite morphology could be noticeably changed in animals exposed to 150 μmol/L of Pb, Cu, and Ag. Furthermore, we observed significant decreases of chemotaxis to water-soluble attractants in Pb exposed che-1 mutant at concentrations more than 2.5 μmol/L, and in Cu, Ag, and Cr exposed che-1 mutant at concentrations more than 50 μmol/L. Therefore, impairment of the ASE neuron structures and functions may largely contribute to the appearance of chemotaxis defects to water-soluble attractants in metal exposed nematodes.

Previous studies have revealed that metal exposure will cause severe deficits in perception behaviors. Here we investigated the effects of metal (Hg, Cu, Ag, and Cr) exposure on thermotaxis to cultivation temperature in Caenorhabditis elegans. Our data suggest that exposure to higher concentrations of examined metals induced severe deficits in thermotaxis, and a significant reduction in thermotaxis could be even observed in nematodes exposed to 2.5μM of Hg. Moreover, exposure to higher concentrations of examined metals and 2.5μM of Hg induced significant decreases in relative intensities and relative sizes of fluorescent puncta of cell bodies in AFD thermosensory neurons. In addition, exposure to higher concentrations of examined metals resulted in a significant reduction in relative intensities and relative lengths of sensory endings in AFD neurons. Furthermore, the relative transcript levels of ttx-1, which functions in specifying the fate of AFD neuron, were significantly decreased in nematodes exposed to 2.5μM of Hg, and 50 and 100μM of examined metals. Thus, metal exposure at high concentrations will induce the severe deficits in thermotaxis to cultivation temperature possibly by altering the morphology or development of AFD neuron and damaging the molecular basis for function of AFD neuron in nematodes.

The synthesis, structure, and single- and two-photon spectroscopic properties of a series of pyrimidine-based (bent-shaped) molecules are reported. All these stable heterocyclic compounds are fully characterized, and exhibit intense single- and two-photon excited fluorescence (SPEF and TPEF) over a wide spectral range from blue to red, with the spectral peak position of the SPEF being basically the same as that of the TPEF. The well-conjugated pi-systems, observed from the crystal structure, indicate the charge transfer feature of the ground state. Meanwhile, the theoretical and experimental studies indicate that the charge transfer from donor to acceptor is greatly enhanced in the excited states and the different substituted donor groups on the pyrimidine have a large effect on the optical and electrochemical properties. Based on typical structure data and comprehensive spectral data, the following structure-property relationships can be determined: for such bent-shaped chromophores, the absorption and the fluorescence wavelength maximum of the SPEF and TPEF, and two-photon absorption cross sections show a similar trend with increasing electron-donating strength of the corresponding terminal group and the number of branches, while the average bond lengths of the pi-linkage and HOMO-LUMO energy levels show an inverse trend. Experimental data and theoretical calculation provide a coherent picture. With these findings, bent-shaped quadrupolar chromophores combining peak TPA cross sections (up to 2280 GM), broad TPA bands throughout the whole 700-900 nm range, and high fluorescence quantum yields could, thus, be obtained. Such compounds are of particular interest for TPEF microscopy, as well as optical data storage in the visible and NIR regions. A data recording experiment proved the potential application of these materials.

Lethality changes were investigated during development in 4 h metal exposed Caenorhabditis elegans. Exposure to examined metals caused severe lethality toxicities in L1- and L2-larvae, in L3-larvae exposed to examined metals at concentrations of 50 and 100 μM and to Pb, Hg, and Cr at the concentration of 2.5 μM, in L4-larvae exposed to examined metals at concentrations of 50 and 100 μM, and in adults exposed to Pb, Hg, and Cr at the concentration of 100 μM. Moreover, the lethality toxicities induced by Pb and Hg in L1 larvae for 4 h could be largely comparable to those in young adults for 24 h.

In this study, we investigated the locomotion behavior changes at different developmental stages in Caenorhabditis elegans exposed to metals for 4h. No obvious differences could be observed in young adults exposed to examined metals, and only exposure to 100 microM of examined metals could significantly decrease the locomotion behaviors of L4 larvae. In contrast, exposure to 50 and 100 microM of examined metals induced noticeable repression of locomotion behaviors at L1-L3 larval stages, and a significant decrease of locomotion behaviors could be observed in L1 larvae exposed to Pb and Hg, and in L2 larvae exposed to Hg at the concentration of 2.5 microM. Moreover, the L1-, L2-, and L3-larvae exposed to metals for 4h exhibited similar neurobehavioral toxicity manner to L4-larvae exposed to metals for 24h. Therefore, younger larvae showed more severe deficits in neurobehavioral phenotypes than L4 larvae and young adults in metal-exposed nematodes.

The one-photon and two-photon absorption properties of a series of dibenzothiophene derivatives are investigated by use of the analytic response theory at DFT level. The numerical results show that these molecules have relatively strong two-photon absorption cross-sections. In the visible light region, the maximal one-photon absorption strengths of the molecules occur in the first excited state. (E,E)-1,4-Bis[3-vinyl-dibenzothiophene]-2,5-dimethoxybenzene molecule has the largest values for both one-photon absorption intensity and two-photon absorption cross-section among the studied molecules. Furthermore, it is shown that the maximal one-photon absorption intensity is monotonically increased as the electron-donating ability of donor group is enhanced. However, the two-photon absorption cross-section displays a non-monotonic increment. The charge-transfer process is analyzed when the molecule is excited from the ground state to charge-transfer state. A general agreement with experimental measurement is obtained.

Locomotion behaviors are susceptible to disruption by a broad spectrum of chemicals and environmental stresses. However, no systematic testing of locomotion behavior defects induced by metal exposure has been conducted in the model organism of nematode Caenorhabditis elegans. In this study, the acute toxicity from heavy metal exposure on the locomotion behaviors was analyzed in nematodes. Endpoints of head thrash, body bend, forward turn, backward turn, and Omega/U turn were chosen to evaluate the locomotion behavioral defects. Our data suggest that the endpoints of head thrash, body bend, and forward turn will be useful for the evaluation of heavy metal toxicity in nematodes. The endpoint of head thrash could detect the toxicity from Cd, Co, Cr, Cu, Hg, and Pb exposures at a low concentration (2.5 μmol/L). The endpoint of body bend could be explored to evaluate the toxicity from all assayed heavy metal exposures at different concentrations, whereas the endpoint of forward turn will be more useful for the evaluation of heavy metal toxicity at high concentrations. Thus, endpoints of these locomotion behaviors establish a fast and economic way to assess the presence of acute toxicity from heavy metal exposure in nematode C. elegans.

Time-dependent hybrid density functional theory in combination with Onsager reaction field model and supermolecular model has been applied to study solvent effects on the geometrical and electronic structures, as well as one/two-photon absorption properties, of 4- (N- (2-hydroxyethyl)-N- methyl) - amino- 4'-nitroazobenzene. It is found that the short-range interaction has a large effect on the electronic structure of the solute molecule, namely, large red-shift of the maximum one-photon absorption is induced by hydrogen bonding. The solute molecule has a large two-photon absorption cross section, which is enhanced by the solvent effect. The computational results are in good agreement with measurements.