Reaction between peroxidized phospholipid and protein: II. Molecular weight and phosphorus content of albumin after reaction with peroxidized cardiolipin

Peroxidized cardiolipin (diphosphatidylglycerol) reacts covalently with albumin. Incubation of albumin with increasing amounts of peroxidized cardiolipin produces a gradual increase in molecular size. Incubation with a small amount of peroxidized cardiolipin (molar ratio of cardiolipin/albumin 21) produces a mixture of complexes that differs considerably with respect to the number of cardiolipin molecules bound per molecule of albumin. With larger amounts of peroxidized cardiolipin (molar ratios of cardiolipin/albumin 54 and 114), the complexes formed seem to be of a more uniform type since the numbers of cardiolipin molecules bound per molecule of albumin are similar. No polymerization occurs for reactions in which up to at least 15 moles of cardiolipin have become bound per mole of albumin, and 20–25 moles may be bound with only very little polymerization. Only when the ratio of peroxidized cardiolipin to albumin was increased to a high value of 314 did polymerization occur. The present findings show that extensive covalent binding of peroxidized cardiolipin to albumin can occur without intermolecular crosslinking of the protein.     

Non-Enzymatic Browning Reactions of Phospholipids

The formation and properties of the fluorescent compounds originated in the browning reactions of phospholipids have been investigated. The compounds exhibited fluorescence with excitation maximum 345–350 nm and emission maximum at 420–430 nm, which were similar to those of lipofuscin and fluorescent substances derived from the reaction of oxidized fatty acids with glutathione. The fluorescence of the compound was affected neither with the pH 2–11 nor by treatment with sodium borohydride. The fluorescent compounds formed in the browning reaction of peroxidized phosphatidylethanolamine are produced, mainly, by interaction of the amine group of phosphatidylethanolamine and saturated aldehydes produced through the decomposition of fatty acid hydroperoxides of phosphatidylethanolamine. Phospholipids do not interact per se with bovine serum albumin, and their interaction is similar to that of polyunsaturated fatty acid hydroperoxides: the phospholipids give secondary products (aldehydes) that subsequently react with protein.     

A Genetically Encoded Diazirine Analogue for RNA–Protein Photo-crosslinking

Ultraviolent crosslinking is a key experimental step in the numerous protocols that have been developed for capturing and dissecting RNA–protein interactions in living cells. UV crosslinking covalently stalls dynamic interactions between RNAs and the directly contacting RNA-binding proteins and enables stringent denaturing downstream purification conditions needed for the enrichment and biochemical analysis of RNA–protein complexes. Despite its popularity, conventional 254 nm UV crosslinking possesses a set of intrinsic drawbacks, with the low photochemical efficiency being the central caveat. Here we show that genetically encoded photoreactive unnatural amino acids bearing a dialkyl diazirine photoreactive group can address this problem. Using the human iron regulatory protein 1 (IRP1) as a model RNA-binding protein, we show that the photoreactive amino acids can be introduced into the protein without diminishing its RNA-binding properties. A sevenfold increase in the crosslinking efficiency compared to conventional 254 nm UV crosslinking was achieved using the diazirine-based unnatural amino acid DiAzKs. This finding opens an avenue for new applications of the unnatural amino acids in studying RNA–protein interactions.     

Fluorescent products from reaction of peroxidizing polyunsaturated fatty acids with phosphatidyl ethanolamine and phenylalanine

Fluorescent chromophores produced by reaction of peroxidizing arachidonic acid or methyl docosahexaenoate with synthetic dipalmityl phosphatidyl ethanolamine were lipid soluble, and those from reaction with phenylalanine were water soluble. In all reaction systems that contained polyunsaturated fatty acid and only one amine compound, the development of fluorescence was linearly related to oxygen absorption for 12–24 hr (p<0.001) and to the amount of thiobarbituric acid reacting materials until the rate of oxygen absorption decreased. The fluorochromes typically had maximum excitation at 360 nm and maximum emission at 430–440 nm, indicating that they were conjugated Schiff bases with the general structure R−N=C−C=C−N−R, where R represents the amino acid phenylalanine or the phospholipid phosphatidyl ethanolamine. The fluorochromes were similar to those extracted from isolated age pigments and tissues of animals that are aged, vitamin E-deficient, or stressed with highly unsaturated lipid diets.     

基于罗丹明B的有机荧光探针合成及Cu~(2+)检测

基于罗丹明B合成了两种有机荧光探针用来检测Cu~(2+)。以罗丹明B与3-甲氧基苯酰肼、水杨酰肼为原料合成了两种探针,命名为Rh1、Rh2,分别与Cu~(2+)以及其它金属离子溶液反应,观察溶液的颜色变化,分别测定其紫外及荧光吸收光谱。Rh1、Rh2加入铜离子溶液后,溶液由无色到粉红色的显著颜色变化,与其它金属离子比较在400～700nm有较明显的紫外-可见吸收和荧光增强。两种荧光探针能够有效的跟Cu~(2+)结合,从紫外-可见吸收光谱和荧光光谱可以看出此探针显示出选择性的、敏感的荧光增强反应,表现出对Cu~(2+)良好的选择性。     

Photoyellowing of milled Wood Lignin and Peroxide-Bleached Milled Wood Lignin in Solid 2-Hydroxypropylcellulose Films After Sodium Borohydride Reduction and Catalytic Hydrogenation in Solution: a Fluorescence Spectroscopic

Fluorescence spectra and emission quantum yields of 2-hydroxypropyl-cellulose films, incorporating milled wood lignin that had been treated in solution by HgOg/NaOH and/or NaBfy and/or H₂ (Pd/C), were measured before and after irradiation by UV light (λ> 300 nm). Bleaching, reduction (NaBH₄), and hydrogenation (H₂, Pd/C) increase the quantum yield of fluorescence and emission in the blue region (400 nm). The destruction of carbonyl chromophores (α-carbonyl, coniferaldehyde, and quinones), which quench the fluorescence of biphenyl groups, the main structures emitting in this part of the spectrum, appeared to be mainly responsible for this increase. Irradiation restores i) emission in the long wavelength part of the spectra (maximum emission: 500 nm, maximum excitation: 400 nm), and ii) quenching of the fluorescence in the blue part (400 nm) of the spectra, even for hydrogenated films. These results are interpretated in relation to the formation, under irradiation, of coniferaldehyde groups and also the generation of complex structures formed by photooxidation of phenolic biphenyls.     

Free Radicals and ROS Induce Protein Denaturation by UV Photostability Assay

Oxidative stress, photo-oxidation, and photosensitizers are activated by UV irradiation and are affecting the photo-stability of proteins. Understanding the mechanisms that govern protein photo-stability is essential for its control enabling enhancement or reduction. Currently, two major mechanisms for protein denaturation induced by UV irradiation are available: one generated by the local heating of water molecules bound to the proteins and the other by the formation of reactive free radicals. To discriminate which is the likely or dominant mechanism we have studied the effects of thermal and UV denaturation of aqueous protein solutions with and without DHR-123 as fluorogenic probe using circular dichroism (CD), synchrotron radiation circular dichroism (SRCD), and fluorescence spectroscopies. The results indicated that the mechanism of protein denaturation induced by VUV and far-UV irradiation were mediated by the formation of reactive free radicals (FR) and reactive oxygen species (ROS). The development at Diamond B23 beamline for SRCD of a novel protein UV photo-stability assay based on consecutive repeated CD measurements in the far-UV (180–250 nm) region has been successfully used to assess and characterize the photo-stability of protein formulations and ligand binding interactions, in particular for ligand molecules devoid of significant UV absorption.     

含手性原子硝基苯胺衍生物的合成及SHG效应

有机非线性光学材料具有ＳＨＧ活性高、响应时间快、分子结构可变性等优点。合成了２０个含不对称原子氨基酸取代的苯系化合物，测试了这些化合物的旋光度、紫外一可见吸收、ＳＨＧ效应，发现１７个化合物具有ＳＨＧ活性，初步探讨了影响ＳＨＧ效应的有关因素。     

Fluorospectroscopic analysis of the fluorescent substances in peroxidized microsomes of rat liver

The fluorescent substances formed in rat liver microsomes in the course of lipid peroxidation were investigated by fluorescence techniques. The fluorescence emitted from peroxidizing microsomes continuously increased as lipid peroxidation progressed, while the steady-state fluorescence anisotropy increased and then reached a plateau. A similar increase was observed in the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in peroxidizing microsomes. The fluorescence from peroxidized microsomes consisted of at least three species having short, middle or long fluorescence lifetimes. The lifetimes and relative amplitudes of fluorescence were unaffected by the extent of lipid peroxidation. Both fluorescence of the chromolipids extracted and the proteins isolated from peroxidized microsomes had the same characteristics in fluorescence lifetimes as the fluorescence from whole peroxidized microsomes. Thus, these lipids and proteins appear to be the major biological substances responsible for the fluorescence emanating from whole peroxidized microsomes. Furthermore, fluorescent substances formed in microsomes seem to increase in quantity rather than change in quality as lipid peroxidation progresses.     

EVA/铕配合物薄膜的制备及光学性能研究

通过溶液浇铸法将四元铕配合物掺杂到乙烯醋酸乙烯酯（EVA）中交联固化得到EVA复合膜,优化了制备EVA膜时固化温度、固化时间和引发剂加入量等工艺条件。通过紫外可见光光谱、荧光光谱研究了EVA复合膜的光学性能。结果表明,配合物在EVA中均匀分散;其掺杂量为1 %时,EVA复合膜具有良好的可见光透过率,对200~400 nm的紫外光有强吸收,并且能够发射出较强的红色荧光。     

Evidence of poly-condensed aromatic rings in a Victorian brown coal

An attempt was made for obtaining UV/VIS absorption and fluorescence spectra of a whole Victorian brown coal and then examining the presence of aromatic ring systems (ARSs) with poly-condensed rings in the coal. Loy Yang brown coal was subjected to an alkali-promoted depolymerization in an aqueous solution of sodium hydroxide at 473 K and then dissolved nearly completely into the solution. The solution of the solubilized coal was analyzed by UV/VIS absorption and fluorescence spectroscopies. The spectra of the solubilized coal were compared with those of a tar that was produced from the rapid pyrolysis of the coal in a wire-mesh reactor. Absorbance of the solubilized coal per unit molar concentration of aromatic carbon and unit light path length was averaged over 50 nm wavelength intervals in a range from 250 to 600 nm. The averaged absorbance of the solubilized coal was much greater than those of mono-aromatic compounds and lignin at intervals from 400 to 600 nm while comparable to those of tetra- to hexa-aromatic compounds, suggesting that the coal is abundant of ARSs with poly-condensed rings. The fluorescence spectra of the solubilized coal also give indication of the presence of ARSs with three to six condensed rings. Furthermore, the presence of even larger ARSs is evidenced from appreciable difference in apparent quantum yield of the solubilized coal and that of the tar. By comparing the absorption and fluorescence spectra of the solubilized coal with those of the tar, it was revealed that the tar is richer in relatively small poly-ARSs than the solubilized coal while the larger poly-ARSs are abundant in the solubilized coal. Smaller poly-ARSs were thus released from the coal preferentially to larger poly-ARSs during the pyrolysis.     

Effect of oxidation on chemical spectral and immunochemical properties of egg yolk lipoprotein

Studies are reported on the changes in the chemical, spectral, and immunochemical properties of the low density lipoprotein fraction of hen's egg yolk during oxidation. Sonication for 15 min at 15–20 C in the presence or absence of iron gave an increase in thiobarbituric value and UV absorption but did not influence the fluorescence. Storage at 50 C in the absence of iron after sonication for 15 min at 15–20 C produced increases in absorptivity in the fluorescence and UV spectra, as well as thiobarbituric values. Similar changes were produced without sonication in the presence of iron in ca. 8 days storage at 50 C. Ethylenediaminetetraacetic acid completely inhibited the effect of copper, as well as iron, under these conditions. Immunoelectrophoresis pattern was effected by oxidation under conditions that gave an increase in absorptivity in the fluorescence spectra. The first change appeared to involve a minor fast moving component which decreased even when oxidation was inhibited by ethylenediaminetetraacetic acid. As the oxidation proceeded, the mobility of the major component in the immunoelectrophoresis analysis was altered. The major reaction affecting the immunochemical properties appeared to be between the product of lipid oxidation and the protein moiety.     

Fluorescent modification of serum albumin by lipid peroxidation

Peroxidation of fatty acids bound to human serum albumin results in the production of fluorescent chromophores in the protein when it is stored in the liquid, powdered or crystalline state. Peroxidizing polyunsaturated fatty acid esters, and carbonyls derived from peroxidizing lipids react with amino groups of protein to give products that have fluorescence spectra very similar to those observed for stored commercial preparations of serum albumin.     

Effect of pH on a gossypol complex with phospholipids: Gossypol-PE

PE, one of the major phospholipids in oilseed soapstock, may react with gossypol to form Schiff bases. PE amounts to 20–30% of the phosphorus compounds in soap-stock. In this report, the dependence on pH of the Schiff base products between PE and gossypol was investigated using a spectrophotometer, an HPLC equipped with an ELSD, and an LC-MS system. We observed that at pH 7 the Schiff reaction product and reactants were clearly detected by ELSD, absorption, and LC-MS spectra. The absorption spectra displayed the characteristic peak for the Schiff bases around 430–440 nm. The absorption spectra also indicated that the reaction was pH dependent. The reaction temperatures were 60 and 90°C. The LC-MS spectra supported the formation of Schiff bases as well as methyl ether derivatives of gossypol in alcohol at the elevated temperatures. The implications of these experimental findings are presented in this paper.     

水杨醛缩芳香胺席佛碱稀土配合物的合成及其光谱性质

合成了一系列水杨醛缩芳香胺席佛碱稀土配合物,研究了它们的红外光谱、紫外可见光谱及荧光光谱性质。与配体相比,配合物的红外特征键C=N吸收波数有减小趋势,紫外光谱中出现新的长波长吸收带,荧光光谱为属离子微扰配体发光。     

稀土紫外荧光防伪油墨的制备

合成了稀土有机配合物Ｅｕ（ＴＦＡ）_３ｐｈｅｎ、Ｅｕ（Ｙ）（ＴＴＡ）_３ｐｈｅｎ,该类配合物能在紫外光激发下（λ_（ｅｘ）＝３８６ｎｍ）发出强可见光红光（λ_（ｅｍ）＝６１９ｎｍ）,稀土元素Ｙ对Ｅｕ（ＴＴＡ）_３ｐｈｅｎ具有荧光增强作用,以增强稀土荧光粉Ｅｕ（Ｙ）（ＴＴＡ）_３Ｐｈｅｎ制备紫外荧光防伪油墨。     

Addition compounds of oxidizing tocopherol and soybean lecithin

Evidence is presented for the formation of addition compounds from tocopherol and soybean lecithin, when adsorbed in monolayer on silica from a mixed solution in chloroform and oxidized at 80 C for 72 hr. Tocopherol was present at 7 mol % of the lecithin in the monolayer. The compounds produced are analogous to linoleic acid-tocopherol adducts previously reported by us. UV spectra of the mixed lecithin and tocopherol monolayers while in silica gel slurry in a solvent were obtained by the method previously reported by us for oxidized linoleic acid and tocopherol monolayers. The monolayer spectra show no evidence for tocopherol dimer. A minor amount of quinone is indicated, but the spectrum has a maximum at 287 nm with no other major peaks. The proposed addition compounds have been characterized by transesterification and hydrogenation, UV, IR, thin layer chromatography and gas chromatography retention behavior, mass spectrometry and elemental analysis. IR spectra of twice-chromatographed addition compounds show specific lecithin absorption bands (5.75 μ; 10.3 μ) together with much enhanced 3.4–3.5, 6.8, 7.25 and 9.14 μ peaks, the latter two being characteristic of α-tocopherol. The UV spectrum of the adducts showed λ _max ^CHCl 3 287 nm, with shoulders at 276 and 300 nm. Hydrogenation removed the peaks at 287 and 276 nm, leaving a peak at 300 nm similar to that of the linoleic acid-tocopherol adduct. Esters of the adducts prepared by transesterification and hydrogenation were similar by all our chemical, chromatographic and spectral tests to the previously characterized esters of the linoleic acid-tocopherol adduct. Paper No. TP-1225 in the U.S. Army Natick Labs. Series.     

A water-soluble D–π–A chromophore based on dipicolinic acid: Synthesis,pH-dependent spectral properties and two-photon fluorescence cell imaging

The presence of two carboxylic acid groups and two hydroxyl groups within the novel dye, (E)-4-(4-bis(2-hydroxyethyl)amino)styryl)pyridine-2,6-dicarboxylic acid, resulted in good water solubility. The compound's UV absorption and photoluminescence spectra were each highly pH sensitive in acidic solutions and two isobestic points were observed. The TPA cross-section coefficient and two-photon fluorescence cell imaging of the dye were investigated.     

巴塔哥尼亚（阿根延）海洋与河水中腐植酸组成比较

比较了Enga西。海湾海水（大西洋）和丘布特河水（阿根廷的巴塔哥尼亚）中腐殖质的结构。这些腐殖质被分离、纯化后,通过元素分析法,核磁共振法（C13和1H谱）,红外光谱法,紫外吸收法和荧光法等对其结构特性进行了分析鉴定,并以氮含量、氧含量、H／C比、C／N比、红外波段中氮和羧基官能团含量、核磁共振吸收谱线中官能团的斜率系...