核糖核酸酶溶液的拉曼光谱研究

报道了用硝基苯萃取处理前后的核糖核酸酶溶液的拉曼光谱。对其主链构象和侧链构象进行了分析,指出酰胺Ⅰ和酰胺Ⅱ中β一折迭和无规卷曲的构象较为明显,二硫桥键的构象是扭式—扭式—扭式,酪氨酸残基有部分是“埋藏”的。同时指出用硝基苯萃取处理蛋白质溶液是获得高质量拉曼谱图的一个简明有效的方法。     

胰蛋白酶溶液的激光拉曼谱

胰蛋白酶溶液的激光拉曼谱柯惟中，余多慰（南京师范大学南京２１００９７）ＲａｍａｎＳｐｅｃｔｒａｏｆＴｒｙｐｓｉｎｉｎＡｑｕｅｏｕｓＳｏｌｕｔｉｏｎ￥ＫｅＷｅｉｚｈｏｎｇａｎｄＹｕＤｕｏｗｅｉ（ＮａｎｊｉｎｇＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙＮａｊｉｎｇ...     

胰蛋白酶溶液的激光拉曼谱

本文报道了用硝基苯萃取处理前后的胰蛋白酶溶液的拉曼光谱。通过分析酰胺Ⅰ和酰胺Ⅲ的拉曼特征频率，初步推断出该胰蛋白酶是含有α－螺旋、β－折叠和无规卷曲结构。同时对其侧链结构也做了初步分析     

牛血清白蛋白水溶液的激光喇曼谱

本文报道了用硝基苯萃取法获得的牛血清白蛋白水溶液的喇曼光谱.定性地证明了该蛋白质多肽链可能由α-螺旋和无规则卷曲组成,酪氨酸残基在肽链中呈全“暴露”式,硫-硫键部位的几何构型为反式-扭式-扭式.     

重组人B淋巴细胞刺激因子的激光拉曼光谱

人B淋巴细胞刺激因子(BAFF)是一种由285个氨基酸组成的Ⅱ型跨膜蛋白质,我们测试了重组的人B淋巴细胞刺激因子(r-BAFF)固体粉末和水溶液的拉曼光谱,通过分析酰胺Ⅰ和酰胺Ⅲ的拉曼特征谱带,判断出重组的人B淋巴细胞刺激因子(r-BAFF)固体粉末状态下构象全为β-折叠结构和β-回转结构,而在水溶液中的二级结构主要仍为β-折叠结构和β-回转结构,另外可能有少量的α-螺旋结构。同时对其侧链构象及环境也做了初步分析。     

紫外辐射对牛血清白蛋白影响的拉曼光谱分析

检测了牛血清白蛋白粉末和水溶液及其经过40min、3h、5h和8h紫外辐射的拉曼光谱图。实验结果表明紫外辐射改变了牛血清白蛋白中硫硫键的几何构型,40min的紫外辐射使牛血清白蛋白粉末中一半以上的硫硫键由“扭式-扭式-扭式”构型变成了“反式-扭式-扭式”构型,经过3h和5h的紫外辐射,从拉曼谱图上已看不到表征硫硫键几何构型的谱峰。40min和3h的紫外辐射使牛血清白蛋白水溶液中部分硫硫键由“扭式-扭式-扭式”构型变成了“反式-扭式-扭式”构型,但当紫外辐射时间长达5h时,硫硫键又只有“扭式-扭式-扭式”一种构型。经过紫外辐射,牛血清白蛋白粉末中酪氨酸残基有由“暴露”式向“埋藏”式转变的趋势;水溶液中一部分酪氨酸残基经紫外辐射后由“暴露”式变成了“埋藏”式。紫外辐射对粉末状态牛血清白蛋白主链构象影响要比溶液状态大。     

Vibrational spectroscopic studies of the structure of di‐amino acid peptides. Part II: cyclo(L‐Asp‐L‐Asp) in the solid state and in aqueous solution

Solid‐state protonated and N,O‐deuterated Fourier transform infrared (IR) and Raman scattering spectra together with the protonated and deuterated Raman spectra in aqueous solution of the cyclic di‐amino acid peptide cyclo(L ‐Asp‐L ‐Asp) are reported. Vibrational band assignments have been made on the basis of comparisons with previously cited literature values for diketopiperazine (DKP) derivatives and normal coordinate analyses for both the protonated and deuterated species based upon DFT calculations at the B3‐LYP/cc‐pVDZ level of the isolated molecule in the gas phase. The calculated minimum energy structure for cyclo(L ‐Asp‐L ‐Asp), assuming C₂ symmetry, predicts a boat conformation for the DKP ring with both the two L ‐aspartyl side chains being folded slightly above the ring. The CO stretching vibrations have been assigned for the side‐chain carboxylic acid group (e.g. at 1693 and 1670 cm⁻¹ in the Raman spectrum) and the cis amide I bands (e.g. at 1660 cm⁻¹ in the Raman spectrum). The presence of two bands for the carboxylic acid CO stretching modes in the solid‐state Raman spectrum can be accounted for by factor group splitting of the two nonequivalent molecules in a crystallographic unit cell. The cis amide II band is observed at 1489 cm⁻¹ in the solid‐state Raman spectrum, which is in agreement with results for cyclic di‐amino acid peptide molecules examined previously in the solid state, where the DKP ring adopts a boat conformation. Additionally, it also appears that as the molecular mass of the substituent on the C^α atom is increased, the amide II band wavenumber decreases to below 1500 cm⁻¹; this may be a consequence of increased strain on the DKP ring. The cis amide II Raman band is characterized by its relatively small deuterium shift (29 cm⁻¹), which indicates that this band has a smaller N H bending contribution than the trans amide II vibrational band observed for linear peptides. Copyright © 2009 John Wiley & Sons, Ltd.     

IR/Raman spectroscopy and DFT calculations of cyclic di‐amino acid peptides. Part III: comparison of solid state and solution structures of cyclo(L‐Ser‐L‐Ser)

B3‐LYP/cc‐pVDZ calculations of the gas‐phase structure and vibrational spectra of the isolated molecule cyclo(L ‐Ser‐L ‐Ser), a cyclic di‐amino acid peptide (CDAP), were carried out by assuming C₂ symmetry. It is predicted that the minimum‐energy structure is a boat conformation for the diketopiperazine (DKP) ring with both L ‐seryl side chains being folded slightly above the ring. An additional structure of higher energy (15.16 kJ mol⁻¹) has been calculated for a DKP ring with a planar geometry, although in this case two fundamental vibrations have been calculated with imaginary wavenumbers. The reported X‐ray crystallographic structure of cyclo(L ‐Ser‐L ‐Ser), shows that the DKP ring displays a near‐planar conformation, with both the two L ‐seryl side chains being folded above the ring. It is hypothesized that the crystal packing forces constrain the DKP ring in a planar conformation and it is probable that the lower energy boat conformation may prevail in the aqueous environment. Raman scattering and Fourier‐transform infrared (FT‐IR) spectra of solid state and aqueous solution samples of cyclo(L ‐Ser‐L ‐Ser) are reported and discussed. Vibrational band assignments have been made on the basis of comparisons with the calculated vibrational spectra and band wavenumber shifts upon deuteration of labile protons. The experimental Raman and IR results for solid‐state samples show characteristic amide I vibrations which are split (Raman: 1661 and 1687 cm⁻¹, IR: 1666 and 1680 cm⁻¹), possibly due to interactions between molecules in a crystallographic unit cell. The cis amide I band is differentiated by its deuterium shift of ∼30 cm⁻¹, which is larger than that previously reported for trans amide I deuterium shifts. A cis amide II mode has been assigned to a Raman band located at 1520 cm⁻¹. The occurrence of this cis amide II mode at a wavenumber above 1500 cm⁻¹ concurs with results of previously examined CDAP molecules with low molecular weight substituents on the C^α atoms, and is also indicative of a relatively unstrained DKP ring. Copyright © 2009 John Wiley & Sons, Ltd.     

几种消除蛋白质分子荧光方法的比较

对高荧光产率的蛋白质分子,用几种方法进行荧光猝灭实验以获取拉曼信号。如变换激发激光波长、以小功率激光长时间照射样品、以较大功率激光照射样品、表面增强拉曼散射及硝基苯萃取法,对此做了比较研究,发现消除牛血清白蛋白水溶液样品荧光的最佳方法是硝基苯萃取法,并给出由此得到的激光拉曼谱。     

FT—Raman挑谱研究溶菌酶在氘代甲醇溶液中的构象变化

用ＦＴ－Ｒａｍａｎ光谱研究了在不同浓度的氘代甲醇－重水溶液中溶菌酶的构象。结果表明,随着氘代甲醇浓度的增加,溶菌酶结构逐渐松散,并形成凝胶。松散β－折叠结构增多是产生凝胶的原因。     

Interactions of lactoferricin B derivatives with model cell membrane studied by Raman spectroscopy

In this work, we employed Raman spectroscopy to study the effect of the antimicrobial peptide lactoferricin B (LfB) on model cell membranes. We used two derivatives of LfB (RRWQWRMKKLG and RRWQWR) with broad‐spectrum activity against gram‐positive and gram‐negative bacteria, fungus, viruses and tumors. Raman spectra of the peptides showed no conformational change in the temperature range 4–60 °C. The positions of the amide I and amide III bands suggest that in an aqueous solution these peptides preferentially adopt a random coil‐like conformation. We also investigated the effect the peptides had on the melting behavior of model cell membranes composed of zwitterionic lipid dipalmitoylglycero‐phosphocholine (DPPC) and anionic lipid dipalmitoylglycero‐phosphoglycerol (DPPG). Raman CH stretching bands were used to follow the melting of the lipid vesicles. We found that the melting of DPPC lipid vesicles is not affected by the presence of the peptides, while the presence of the peptides reduced cooperativity of the phase transition for anionic DPPG vesicle, suggesting that both peptides interact strongly and specifically with this model cell membrane composed of anionic lipid. Copyright © 2006 John Wiley & Sons, Ltd.     

热处理和紫外辐射对DNA影响的拉曼光谱研究

检测了鲕鱼精ＤＮＡ纤维和经过４０℃，９１℃，２００℃加热处理的拉曼光谱。研究结果表明，在熔融温度以下热处理对ＤＮＡ构象的影响是轻微的，在熔融温度以上则随温度的升高，对ＤＮＡ分子结构的影响有破坏也逐渐加剧，首先受影响的是腺嘌呤和脱氧核糖。     

Monitoring of spectroscopic changes of a single trapped fission yeast cell by using a Raman tweezers set-up

We demonstrate an improvement of the sensitivity of a Raman tweezers set-up, which combines optical tweezers with Raman spectroscopy. The system was tested by taking the Raman spectrum of a 4.6 μm diameter polystyrene sphere trapped in an aqueous solution. The improvement of sensitivity of the set-up was achieved by adjusting the trap depth for maximum signal to noise ratio (SNR). The maximum SNR was obtained by investigating the Raman peak of a trapped polystyrene sphere at 1001 cm⁻¹ according to trap depth. With this system, a single trapped living Schizosaccharomyces Pombe yeast cell was sensitively monitored by taking the kinetic Raman spectra for more than 2 h. The relative intensity decrease in amide I and amide III bands, frequency increase in amide I band together with alterations in tyrosine marker band around 850 cm⁻¹ was observed, which indicates alterations in the hydration state of protein by time progressing.     

温度对鱼鳞胶原蛋白二级结构的影响

从草鱼鱼鳞中提取酶溶性胶原蛋白(PSC),通过SDS-PAGE电泳分析为典型Ⅰ型胶原蛋白且达到电泳纯。在此基础上利用傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)和圆二色谱(CD)研究了温度对鱼鳞胶原蛋白二级结构的影响。FTIR分析表明：鱼鳞胶原蛋白具有典型的胶原蛋白特征吸收带,酰胺Ⅰ、酰胺Ⅱ和酰胺Ⅲ带的特征吸收频率分别出现在1658,1552和1238cm-1处。随温度升高,酰胺A和酰胺B峰位向低波数移动,1658cm-1处吸收峰裂解成多个吸收峰;1552cm-1处的吸收峰在35℃微略红移,随后发生明显蓝移;1238cm-1处吸收峰随温度升高向低波数移动。在拉曼光谱中,胶原蛋白的酰胺Ⅰ、酰胺Ⅱ和酰胺Ⅲ带的特征吸收频率分别出现在1669,1557和1245cm-1处,都较红外光谱的波数高;此外,921和855cm-1处脯氨酸的特征谱峰在拉曼光谱中体现出来。圆二色谱分析表明,胶原蛋白溶液在221.6和204.4nm分别有一正、负峰,具有典型胶原蛋白三螺旋结构的特征圆二色谱峰型。胶原蛋白冻干品的FTIR光谱和Raman谱线大都在35～60℃时发生波数和强度改变,而胶原蛋白乙酸溶液的CD谱线在20～35℃之间发生剧烈改变。由此可以判断胶原蛋白在固态和溶液状态下,变性温度存在一定差异,胶原蛋白冻干品比其乙酸溶液更稳定。     

Micro‐Raman study of PET single fibres under high hydrostatic pressure: phase/conformation transition and amorphization

The micro/nano structural evolution of a PET single fibre under hydrostatic pressure has been studied by Raman micro spectroscopy in a diamond anvil cell (DAC). Different bands in the Raman spectra were used as probes: the low wavenumber collective modes (<250 cm⁻¹) representative of the long‐range chain organization, as well as the stretching and bending amide and aromatic ring modes representative of the local chain behaviour. The in situ analysis at different pressures shows an evolution from an axial oriented trans‐conformation to an amorphous, isotropic material, i.e. the reverse transformation observed during the process of drawing the fibre from an isotropic amorphous precursor. Copyright © 2007 John Wiley & Sons, Ltd.     

Vibrational spectra and crystal structure of the di‐amino acid peptide cyclo(L‐Met‐L‐Met): comparison of experimental data and DFT calculations

Experimental Raman and FT‐IR spectra of solid‐state non‐deuterated and N‐deuterated samples of cyclo(L ‐Met‐L ‐Met) are reported and discussed. The Raman and FT‐IR results show characteristic amide I vibrations (Raman: 1649 cm⁻¹, infrared: 1675 cm⁻¹) for molecules exhibiting a cis amide conformation. A Raman band, assigned to the cis amide II vibrational mode, is observed at ∼1493 cm⁻¹ but no IR band is observed in this region. Cyclo(L ‐Met‐L ‐Met) crystallises in the triclinic space group P1 with one molecule per unit cell. The overall shape of the diketopiperazine (DKP) ring displays a (slightly distorted) boat conformation. The crystal packing employs two strong hydrogen bonds, which traverse the entire crystal via translational repeats. B3‐LYP/cc‐pVDZ calculations of the structure of the molecule predict a boat conformation for the DKP ring, in agreement with the experimentally determined X‐ray structure. Copyright © 2009 John Wiley & Sons, Ltd.     

用拉曼光谱研究抗癌药物落羽松醇和它的类似体

用拉曼光谱研究抗癌药物落羽松醇和它的类似体郑思定，舒莲美，洪田博喜（复旦大学分析测试中心上海２００４３３）（日本岗山理科大学）ＲａｍａｎＳｐｅｃｔｒｏｓｃｏｐｉｃＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔａｘｏｌａｎｄＩｔｓＡｎａｌｏｇｕｅｓ￥ＺｈｅｎｇＳｉｄ...     

Vibrational spectroscopy and DFT calculations of di‐amino acid cyclic peptides. Part I: cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) in the solid state and in aqueous solution

Investigations of the vibrational spectra of cyclo(Gly‐Gly), cyclo(L‐Ala‐L ‐Ala) and cyclo(L ‐Ala‐Gly) are reported. Raman scattering and Fourier transform infrared (FTIR) spectra of solid‐state and aqueous protonated samples, as well as their corresponding N‐deuterated isotopomers, have been examined. In addition, density functional theory (DFT) (B3‐LYP/cc‐pVDZ) calculations of molecular structures and their associated vibrational modes were carried out. In each case, the calculated structures of lowest energy for the isolated gas‐phase molecules have boat conformations. Assignments have been made for the observed Raman and FTIR vibrational bands of the cyclic di‐amino acid peptides (CDAPs) examined. Raman polarization studies of aqueous phase samples are consistent with C₂ and C₁ symmetries for the six‐membered rings of cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly), respectively. There is a good correlation between experimental and calculated vibrational bands for the three CDAPs. These data are in keeping with boat conformations for cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) molecules, predicted by the ab initio calculations, in both the solid and aqueous solution states. However, Raman spectroscopic results might infer that cyclo(L‐Ala‐Gly) deviates only slightly from planarity in the solid state. The potential energy distributions of the amide I and II modes of a cis‐peptide linkage are shown to be significantly different from those of the trans‐peptides. For example, deuterium shifts have shown that the cis‐amide I vibrations found in cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala), and cyclo(L‐Ala‐Gly) have larger N‐H contributions compared to their trans‐amide counterparts. Compared to trans‐amide II vibrations, cis‐amide II vibrations show a considerable decrease in N H character. Copyright © 2009 John Wiley & Sons, Ltd.     

人类唾液蛋白N 端片段的构型

人类唾液蛋白Statherin 是含有43 残基的酸性磷酸化蛋白．此蛋白对磷酸钙具有较高的吸附性,已知其N 端15 残基的片段(SN-15)会吸附于磷灰石的表面．在该工作中,作者以液体核磁共振波谱学研究SN-15 的分子结构．圆二色光谱显示SN-15 在磷酸盐缓冲溶液中具α 螺旋构型．根据高分辨核磁共振氢谱(COSY,TOCSY 及NOESY)作者得到相关的NOE 及J 耦合数据,氢氘交换实验也进一步显示SN-15 具α 螺旋构型．     

不同构型罗丹明分子拉曼光谱的密度泛函理论研究

利用密度泛函理论研究了罗丹明6G、罗丹明123和罗丹明B分子的拉曼光谱. BP86泛函计算的罗丹明系列分子的阳离子在气相中的拉曼光谱与相应的分子在水溶液中的实验光谱符合很好. 结果显示氯离子以及氢键的引入对罗丹明B分子的拉曼光谱有较明显的影响,该影响可以部分地解释罗丹明B分子在水溶液中和在金表面上拉曼光谱的不同. 精确描述罗丹明分子在金属表面的表面增强拉曼光谱,需要考虑由界面相互作用而导致的变化.