天花粉蛋白的化学 Ⅵ.用激光拉曼光谱研究天花粉蛋白的二级结构

由天花粉蛋白的水和重水溶液的激光拉曼光谱,测得酰胺Ⅲ谱带1240cm~(-1)和酰胺I谱带1632,1660cm~(-1)对CH_2弯曲模式1448cm~(-1)的强度比值。按Lippert等建立的方程组作定量计算,求得天花粉蛋白的二级结构含量为α-螺旋43.5％,β-折叠31.3％和无序25.2％,它们与4 分辨率天花粉蛋白单晶X射线衍射法的结果相一致。同时,研究了上述溶液的冻干粉状固体的二级结构,经过冻干,使其中约10％的β-折叠转变成无序构象,而α-螺旋含量无明显变化。在水溶液中,由测得的I_(850)/I_(830)比值计算,天花粉蛋白中的酪氨酸残基约有80％呈“暴露式”。     

用概率统计法估算天花粉蛋白的二级结构

本文应用Levitt提出的蛋白质中氨基酸对二级结构的特定偏爱的统计方法估算天花粉蛋白的二级结构。计算结果表明,在天花粉蛋白中α-螺旋为32％,β-折叠为28％,反转为20％,其他类型为20％。这一计算结果与X射线衍射研究、圆二色性谱研究的结果相近。     

天花粉蛋白的化学VI.用液光拉曼光谱研究天花粉蛋白的二级结构

由天花粉蛋白的水和重水溶液的激光拉曼光谱,测得酰胺III谱带1240cm[-1]和酰胺I谱带1632,1660cm[-1]对CH2弯曲模式1448cm[-1]的强度比值,按Lippert等建立的方程组作定量计算,求得天花粉蛋白的二级结构含量为α-螺旋43.5%,β-折叠31.3%和无序25.2%,它们与4A分辨率天花粉蛋白单晶X射线衍射法的结果相一致,同时,研究了上述溶液的冻干粉状固体的二级结构,经过冻干,使其中约10%的β-折叠转变成无序构象,而α-螺旋含量无明显变化,在水溶液中,由测得的I850/I830比值计算,天花粉蛋白中的酪氨酸残基约有805呈"暴露式"。     

八棱丝瓜蛋白1的二级结构及其生物活性

测定了八棱丝瓜蛋白1的N端顺序为Asp-Val-Ser-Phe-Ser-,用CD谱测定了八棱丝瓜蛋白 1的α螺旋,β-折叠和无规卷曲含量分别为37.1%,33.4%,29.5%。实验表明,八棱丝瓜蛋白 1具有RNA N-糖苷酶活性,体外抑制肿瘤细胞生长活性表明其对肿瘤细胞株B16,MGC,Bel的半数抑制浓度分别为1.78×10-7mol/L,2.11×10-7mol/L和4.21×10-7mol/L。并在N端顺序,二级结构和生物活性方面对八棱丝瓜蛋白 1和天花粉蛋白进行了比较。     

天花粉蛋白溶液构象与稳定性及生物活性的关系

用圆二色性研究了天花粉蛋白在不同PH,不同温度和不同的时间条件下的溶液构象变化.阐明了天花粉蛋白溶液的外部环境,并研究了天花粉蛋白的溶液构象与抗生育活性的关系,结果表明随着溶液中a-helix含量的增加,抗生育活性也相应增加,当a-helix含量减少到15%以下,其抗生育活性也就丧失.     

天花粉蛋白的化学 Ⅲ.溴化氰降解片段CBa的氨基酸顺序

前文已初步报道了天花粉蛋白的理化性质和N-端的部分氨基酸顺序.结晶天花粉蛋白经琥珀酸酐处理所得的琥珀酰天花粉蛋白,在88％甲酸中经溴化氰降解后的产物通过Sephadex G-75凝胶柱层析,可分得6个峰(见图1).     

激光光散射研究天花粉蛋白的聚集过程

运用激光光散射技术研究天花粉蛋白在水溶液及不同浓度KSCN水溶液中的聚集过程．KSCN的加入能提高天花粉在水溶液中的稳定性. KSCN浓度大于0．5mol•L－1时，天花粉溶液透明、稳定，溶液中天花粉以单个分子与聚集体两种形式存在．聚集体主要是由约120个天花粉分子组成，平均流体力学半径Rh值约为49nm，在溶液中排列疏松，类似θ溶剂中的无规线团。     

天花粉蛋白的化学——Ⅴ.粉末状结晶天花粉蛋白的拉曼光谱

本文报道粉末状结晶天花粉蛋白的拉曼光谱。酰胺Ⅰ和酰胺Ⅲ的振动谱带在1680和1250 cm~(-1)。骨架C_α—C—N的振动谱带在965 cm~(-1)。苯丙氨酸残基的特征谱带在1010和1620 cm~(-1)。酪氨酸残基的特征谱带在845和862 cm~(-1)。色氨酸残基的特征谱带在765 cm~(-1)。酰胺Ⅰ和Ⅲ的谱带中,B折叠和无序结构的特征较为明显。表征无序结构的965 cm~(-1)谱带很弱。     

天花粉糖蛋白的分离及部分水解片

在天花粉蛋白研究的早期,曾发现含糖10%以上的粗天花粉蛋白有热原反应,用于临床时,人体明显发热。进一步制得的含糖3%的精制天花粉蛋白也有热原反应,人体发热较粗天花粉蛋白弱。不含糖的纯结晶天花粉蛋白无热原反应,人体发热更弱。     

天花粉蛋白一级结构的修正及不同产地天花粉蛋白的研究

胰蛋白酶酶解天花粉蛋白, 用高效液相色谱分离酶解肽段, 用顺序仪测定其有关肽段的顺序。用羧肽酶A, B, Y测定了天花粉蛋白C-端和天花粉蛋白溴化氰降解肽CB1的C-端顺序, 修正了我们1985年测定的天花粉蛋白一级结构, 证明天花粉蛋白由246(7)氨基酸残基所组成, 除C-端微观不均一外, 与Collins结果一致。同时比较了芜湖产天花粉蛋白一级结构与平湖产的天花粉蛋白一级结构, 没有发现两者的一级结构有差别。     

CIRCULAR DICHROISM OF LIGHT-HARVESTING COMPLEXES FROM PURPLE PHOTOSYNTHETIC BACTERIA*

Abstract— The CD spectra of a range of antenna complexes from several different species of purple photosynthetic bacteria were recorded in the wavelength range of 190 to 930 nm. Analysis of the far UV CD (190 to 250 nm) showed that in each case except for the B800-850 from Chr. vinosum the secondary structure of the light-harvesting complexes contains a large amount of α-helix (?50%) and very little 0-pleated sheet. This confirms the predictions of the group of Zuber of a high a-helical content based upon consideration of the primary structures of several antenna apoproteins. The CD spectra from the carotenoids and the bacteriochlorophylls show considerable variations depending upon the type of antenna complex. The different amplitude ratios in the CD spectrum for the bacteriochlorophyll Qy, Qx and Soret bands indicate not only different degrees of exciton coupling, but also a strong and variable hyperchromism (Scherz and Parson, 1984a, b).     

Electronic and Vibrational Spectra of Fullerenes in Contact with Oxygen

The high-resolution electronic and vibrational spectra of fullerenes C60, C70, and C78 were analyzed. The absorption spectrum of fullerene C60 contains a series of seven well-resolved bands in the range 200-280 nm, the strongest of them being at 240 nm, as well as two broadened bands of lower intensity at 280 and 330 nm. The former seven bands were assigned to vibrationally excited -* transitions in the molecular system of conjugated bonds, and the latter two, to intermolecular interactions in a fullerene-oxygen contact complex. As the molecular weight of the fullerene increases, the short-wave absorption band suffers a hypsochromic shift, which is characteristic of nonalternant aromatic systems. The IR spectra provide evidence for the formation of a contact charge-transfer complex with oxygen by displaying emission and absorption in the region of fundamental frequencies of the triplet, singlet, radical-ion, and ionic states of molecular oxygen.     

Remote Raman and fluorescence studies of mineral samples

In the present study, we investigated remote laser-induced fluorescence (LIF), at a distance of 4.8 m, of a variety of natural minerals and rocks, and Hawaiian Ti (Cordyline terminalis) plant leaves. These minerals included calcite cleavage, calcite onex and calcite travertine, gypsum, fluorapatite, Dover flint and chalk, chalcedony and nephelene syenite, and rubies containing rock. Pulsed laser excitation of the samples at 355 and 266 nm often resulted in strong fluorescence. The LIF bands in the violet-blue region at approximately 413 and approximately 437 nm were observed only in the spectrum of calcite cleavage. The green LIF bands with band maxima in the narrow range of approximately 501-504 nm were observed in the spectra of all the minerals with the exception of the nephelene syenite and ruby rocks. The LIF red bands were observed in the range approximately 685-711 nm in all samples. Excitation with 532 nm wavelength laser gave broad but relatively low fluorescence background in the low-frequency region of the Raman spectra of these minerals. One microsecond signal gating was effective in removing nearly all background fluorescence (with peak at approximately 610 nm) from calcite cleavage Raman spectra, indicating that the fluorescence was probably from long-lifetime inorganic phosphorescence.     

Application of multicomponent spectrophotometry to analytical control of electroplating solutions

Summary A procedure for the simultaneous spectrophotometric determination of organic additives and the quantitation of Ni(II) in Zn-Ni electrolytic baths is described. Organic additives were determined by resolving the mixed spectrum over the wavelength range 278–330 nm by applying a least-squares fitting computational program to the standard spectrum of each component. Spectra were recorded on a hydroalcoholic medium (15% methanol) containing 0.1 mol/l NH₄Cl. The Ni(II) concentration was determined by applying the program to the first-derivative spectrum over the wavelength range 660–820 nm.     

Infrared and circular dichroism spectroscopic characterisation of secondary structure components of a water treatment coagulant protein extracted from Moringa oleifera seeds

The secondary structure of a water treatment coagulant protein extracted from Moringa oleifera (MO) seeds has been investigated by Fourier transform infrared spectroscopy (FTIR) in the dried state, and by circular dichroism (CD) spectroscopy. The FTIR and CD spectra indicate that the secondary structure of the protein is dominated by alpha-helix. The FTIR spectrum recorded two distinct and strong absorption bands at 1656 cm(-1) and 1542 cm(-1), in the usual range of absorption of helices of proteins. The CD spectrum showed the shape of mainly alpha-helical secondary structure (estimated to be 58+/-4%) characteristic of negative ellipticity bands near 222 nm and 208 nm and a positive band at 192 nm. The beta-sheet structure composition was estimated to be 10+/-3% whereas unordered structures were around 33%. Changes in solution pH affected the protein secondary structure significantly only at pH values above 10, as indicated by CD spectra, whereas ionic strength had minimal effect. CD data also showed that sodium dodecyl sulphate (SDS) interacts with the coagulant protein and modifies the protein conformation. The surfactant-induced conformational change of the coagulant protein was confirmed by quenching of tryptophan fluorescence of the protein.     

ACTION SPECTRUM FOR ERYTHEMA IN HUMANS INVESTIGATED WITH DYE LASERS

Abstract— Erythema reactions of human skin were reevaluated with improved experimental methods: a tunable, highly monochromatic irradiation source as well as an instrumental measurement of skin reactions were used. The irradiation system consisted of an excimer laser pumped dye laser and a U V fiber optic system. The skin color after irradiation was determined with a colorimeter in the three-dimensional norm system of the Commission Internationale d'Eclairage (CIE). The wavelength dependence for delayed erythema was investigated in the UVB and UVA region from 294 nm to 374 nm in skin type II and III individuals. The maximum of the action spectrum in the UVB range was measured at 298.5 nm and an additional maximum was found at 362 nm in the UVA range. The action spectrum is compared with previous spectra from the literature and with the current standard erythema curve of the CIE as well as with other photobiological action spectra. Our results suggest a UVA/UVB boundary at 330 nm.     

量子点标记天花粉蛋白的研究

将半导体量子点应用于记天花粉蛋白,研究了量子占标记天花粉蛋白的吸收光谱、荧光光谱和酶活性变化,与游离的QDs 相比,QDs-TCS的吸收光谱在400－600nm范围内不发生明显变化,QDs-TCS的发射光普发生蓝移,但发射半宽不变,标记上QDs后TCS的酶活性没有发生改变,利用双光子激发扫描荧光显微镜和激光共取焦显微镜同时观察QDs-TCS在人绒癌细胞内的分布发现,QDs-TCS能够跨膜进入细胞,并在细胸核周围呈聚集分布。     

The circular dichroism spectrum of S(+)-sec-butyl benzene

The absorption and CD spectra of S(+)-sec-butyl benzene are reported in the spectral region 195–180 nm. The CD spectrum contains two bands of opposite sign at 190.5 nm and 187 nm. The results are interpreted to confirm previous results for 1-methylindan in this spectral region. The observed bands are assigned to the state derived from the benzene E_2g state.     

Jet-discharge cavity ring-down spectroscopy of ionized polycyclic aromatic hydrocarbons: progress in testing the PAH hypothesis for the diffuse interstellar band problem.

Naphthalene cations (C10H+8) were produced in a slit jet coupled with an electronic discharge, and cavity ring down was used to obtain its absorption spectrum in the region 645-680 nm. Two of the strongest C10H+8 bands previously characterized by matrix isolation spectroscopy were found, both with a fractional blue shift of about 0.5%. This is the first gas-phase electronic absorption spectrum of an ionized polycyclic aromatic hydrocarbon (PAH). This work opens the way for a direct comparison of laboratory PAH spectra with the diffuse interstellar bands (DIB), the origin of which still constitutes an open problem in astrophysics.     

Luminescence properties of epoxy resins modified with a carbazole derivative

Luminescence properties of a new material - epoxy resin with added 9-(2,3-epoxypropyl)carbazole (REPK) were studied. Absorption and photoluminescence (PL) spectra of REPK are compared with those of poly(N-vinylcarbazole) (PVK). PL in REPK is shifted to shorter wavelengths. Its intensity is higher than in PVK. REPK emits light in the range from 330 nm to 470 nm. PL spectrum of REPK could be well deconvoluted for four emission bands.