温度与电磁参数协同影响胰岛素分子构象与功能的光谱学方法研究

近年来,脉冲电磁辐射和弱电磁辐射的生物效应已引起人们的关注.开展了众多的病理学调查和实验研究.但是研究结果并不一致,学术界存在众多争议.由于脉冲电磁辐射和弱电磁辐射不能引起被辐照生物样品产生明显的温升效应(温升小于0.1℃),不能用电磁辐射的热效应机理来解释这类生物效应.因此人们往往称之为"非热效应".文章应用荧光光谱和拉曼光谱方法研究脉冲电场对胰岛素分子构象变化影响的结果表明:(1)尽管这类电磁辐射不会引起被辐照生物样品的温度产生明显变化(0.1℃),但是辐照时的环境温度变化则能改变辐照实验的结果.(2)环境温度能对胰岛素分子结构中的链间二硫键,C-C键的振动等在脉冲电场作用下的变化产生明显的影响,从而对脉冲电场引发的胰岛素的构象变化产生影响.这表明对于"非热效应",表征热的量度的温度,仍是脉冲和弱电磁场辐照生物效应研究中值得关注的极重要参数.     

50 Hz脉冲电场作用下胰岛素构象变化的拉曼光谱分析

以激光拉曼光谱为手段,研究了经50 Hz脉冲电场作用后,胰岛素分子构象的变化。分析表明：经50 Hz低频脉冲电场作用后,胰岛素分子的共价键体系仍保持完好,但是分子的氢键体系发生了改变。主要表现在：α螺旋结构遭到破坏,α螺旋相对于β折叠的含量降低,致使酰胺Ⅰ带的峰向高波数方向移动。α螺旋结构的解聚使原本位于螺旋内部的振动暴露。三个二硫键的强度均减弱,且向短波方向稍有移动,也说明其周围的微环境发生了变化。另外,胰岛素二聚体之间的氢键遭破坏,导致相关拉曼峰的出现或者增强。     

应用FTIR法研究磷脂酶A2改性蛋黄粉乳化性的构效关系

乳化性能是磷脂酶A2改性蛋黄粉的重要指标.将磷脂酶A2改性蛋黄液分别在150,170及190℃条件下喷雾干燥制成蛋黄粉,运用FTIR技术并结合去卷积、二阶导数、曲线拟合方法对蛋白质二级结构进行分析.结果表明,随喷雾干燥温度的升高,蛋黄粉的乳化性能及α-螺旋含量均呈现先升高后下降的趋势,蛋黄粉乳化液的热稳定性不受喷雾干燥温度的影响,但二级结构会呈现出从α-螺旋向β-折叠转变的趋势,而代表蛋白质分子内部紧密程度的β+α结构总含量相对稳定.     

FTIR分析脉冲电场和热处理后的大豆分离蛋白结构变化

采用自行研制的脉冲电场设备,利用傅里叶变换红外光谱(FTIR)比较研究了脉冲电场(PEF)和热处理对大豆分离蛋白(SPI)分子结构的影响.结果表明:50 kV·cn-1的脉冲场强处理引起SPI分子内和分子间氢键增强,分子中C-O-O糖苷键伸缩振动和P=O,P-O-C伸缩振动增强,且其增加值与PEF处理时间呈正相关.研究发现较短时间(1 600 μs)PEF处理导致了SPI分子结构中α-螺旋和β-折叠分别减少了5.9%和0.7%,β-转角和侧链结构分别增加了7.5%和9.6%;处理时间延长至2 400 μs,其α-螺旋和β-折叠减少量增至6.0%和5.6%.对比而言,热处理对SPI分子结构中C-O-O糖精苷键伸缩振动和P=O,P-O-C伸缩振动的影响程度较大,而对蛋白质二级结构影响程度较小:90℃热处理30 min,α-螺旋和β-折叠分别减小5.1%和6.6%,β-转角结构增加19.1%.由此可以认为PEF和热处理对SPI的影响机理是不一样的.     

应用圆二色光谱研究电场对脂肪酶二级结构的影响

脂肪酶被不同强度的电场处理5 min,用圆二色光谱(circular dichroism, CD)研究电场对脂肪酶(Lipase)二级结构的影响。研究结果表明：在0.5～6.0 kV·cm-1范围内,不同强度的电场对脂肪酶的α-螺旋、β-折叠、β-转角及无规卷曲相对含量的影响程度不同。随场强的增加,各二级结构单元含量呈非单调变化。电场作用可使脂肪酶二级结构中α-螺旋、β-折叠、β-转角及无规卷曲发生转化。总体上,电场使脂肪酶的二级结构由α-螺旋、β-折叠向转角及无规卷曲转化。α-螺旋含量和β-折叠的含量降低幅度分别为4.6%～48.0%和13.2%～35.1%,β-转角含量与无规卷曲含量增加幅度分别为2.8%～33.3%和0.9%～48.1%。文章结果对研究电场处理植物种子的宏观生物效应作用机理提供了重要理论依据。     

应用圆二色光谱研究电场对超氧化物歧化酶二级结构的影响

超氧化物歧化酶经不同强度的电场作用,采用圆二色光谱研究了不同强度的电场对超氧化物歧化酶二级结构的影响.结果表明：在1.0 kV/cm～6.0 kV/cm范围, 不同强度的电场对超氧化物歧化酶的α-螺旋、β-折叠、β-转角及无规卷曲相对含量的影响程度不同.与对照组相比,处理组的β-折叠和β-转角含量降低,降幅范围分别为2.5%～15.1和0.9%～3.5%；α-螺旋和无规卷曲含量增加,增幅范围分别为3.1%～18.8%和1.0%～8.9%.电场作用具有使超氧化物歧化酶的二级结构中β-折叠、β-转角向α-螺旋及无规卷曲转化的趋势.     

应用圆二色光谱研究电场对辣根过氧化物酶二级结构的影响

辣根过氧化物酶(ＨＲＰ)经不同强度的电场处理,用圆二色光谱研究了电场对辣根过氧化物酶二级结构的影响。结果表明：在1.0～6.0 kV·cm-1范围, 不同强度的电场对辣根过氧化物酶的α-螺旋、β-折叠、β-转角及无规卷曲相对含量的影响程度不同。与对照组相比,处理组的α-螺旋、β-转角和无规卷曲含量降低,降幅范围分别为0.3%～11.4%,1.7%～15.3%和0.9%～20.4%;β-折叠含量增加,增幅范围为0.9%～82.7%。电场作用具有使辣根过氧化物酶的二级结构中α-螺旋、β-转角和无规卷曲向β-折叠转化的趋势。研究结果对解释电场处理种子生物效应具有重要意义。     

丹参酚酸A和丹参酚酸B与胰岛素相互作用的分子光谱学研究以及葡萄糖的影响

采用紫外-可见光谱、荧光光谱和傅里叶变换衰减全反射红外光谱等技术,研究在模拟人体生理Ph值条件下,丹参酚酸A(或丹参酚酸B)与胰岛素分子之间的结合作用,以及丹参酚酸A(或丹参酚酸B)对胰岛素二级结构的影响,并考察葡萄糖对它们的影响。实验结果表明,丹参酚酸A和丹参酚酸B均能导致胰岛素内源性荧光静态猝灭;同步荧光和三维荧光谱图表明胰岛素与丹参酚酸A(或丹参酚酸B)结合后,构象没有发生明显变化。红外光谱研究表明,胰岛素与丹参酚酸A(或丹参酚酸B)结合后二级结构发生了一些改变,β-转角和无规则卷曲的相对含量略有增加,α-螺旋和β-折叠没有发生明显改变。葡萄糖的加入会改变丹参酚酸A(或丹参酚酸B)与胰岛素的结合程度,并加剧胰岛素构象变化以及二级结构中α-螺旋相对含量改变,从而影响丹参酚酸A(或丹参酚酸B)-胰岛素体系中胰岛素的生物活性。     

丹参酚酸A和丹参酚酸B与胰岛素相互作用的分子光谱学研究以及葡萄糖的影响（英文）

采用紫外-可见光谱、荧光光谱和傅里叶变换衰减全反射红外光谱等技术,研究在模拟人体生理Ph值条件下,丹参酚酸A(或丹参酚酸B)与胰岛素分子之间的结合作用,以及丹参酚酸A(或丹参酚酸B)对胰岛素二级结构的影响,并考察葡萄糖对它们的影响。实验结果表明,丹参酚酸A和丹参酚酸B均能导致胰岛素内源性荧光静态猝灭;同步荧光和三维荧光谱图表明胰岛素与丹参酚酸A(或丹参酚酸B)结合后,构象没有发生明显变化。红外光谱研究表明,胰岛素与丹参酚酸A(或丹参酚酸B)结合后二级结构发生了一些改变,β-转角和无规则卷曲的相对含量略有增加,α-螺旋和β-折叠没有发生明显改变。葡萄糖的加入会改变丹参酚酸A(或丹参酚酸B)与胰岛素的结合程度,并加剧胰岛素构象变化以及二级结构中α-螺旋相对含量改变,从而影响丹参酚酸A(或丹参酚酸B)-胰岛素体系中胰岛素的生物活性。     

应用红外光谱研究电场对超氧化物歧化酶二级结构的影响

超氧化物歧化酶经不同强度的电场处理,利用红外光谱法研究电场对超氧化物歧化酶二级结构的影响。结果表明,经不同电场强度处理的超氧化物歧化酶(SOD),其二级结构单元百分含量有不同程度的变化。α-螺旋和β-折叠结构单元在电场处理后,均为减少;β-转角结构单元均为增加;无规卷曲结构单元除4.0 kV·cm-1电场处理条件减少外,其余电场处理条件均为增加。电场处理具有使超氧化物歧化酶的α-螺旋、β-折叠向β-转角和无轨卷曲结构转化的作用,且不同电场条件下其转化情况不同。研究结果还表明,电场的作用使SOD活性发生改变,SOD活性变化与β-折叠含量变化相关。     

Study on temperature & EMF co-effects on insulin conformation and biological functions by fluorescence and Raman spectroscopy

Our previous studies had suggested that the intercellular signal molecule might be an important target of electromagnetic fields. Insulin, an intercellule signal molecule, plays a critical role in transferring life information. The studies on effects of pulsed electric fields (PEF) on insulin molecule are meaningful for explaining the mechanism of biological effects of electromagnetic fields. The PEF, which we used, with its highest electric field (2 x 10(6) V x m(-1)) coupled into the insulin buffer, was about 1 V x cm(-1) cm, with a repeating frequency of 50 Hz. In the present study, the changes of insulin conformation induced by PEF were studied by fluorescence spectroscopy. Insulin solution was exposed to 50 Hz PEF with different electric field intensities for 5-35 min, which caused a time-and dose-dependent decrease in fluorescence intensities of insulin. Further, insulin solution was exposed to PEF at different temperatures to investigate the effects of PEF co-operated with temperature on insulin. The results indicated that the difference in temperature (about 5 degrees C) could induce conflict results, which is due to the effects of PEF co-operated with temperature rather than only to the effect of temperature. The authors calculated that the increase in temperature induced by PEF was 0.07 degrees C (less than 0.1 degrees C). So the effects of PEF were scarcely explained by thermal effects, it belongs to "non-thermal effects" of electric fields. So it was concluded that temperature is a considerably important factor in "non-thermal effects" of electric fields, and the ignorance of variety of temperature probably result in the contrary conclusion. Further, Raman spectroscopy was used to investigate the details of structure of insulin treated by PEF co-operated with temperature. The results of Raman spectroscopy verified the effects of PEF co-operated with temperature on insulin. And the reductions of the S-S band intensity at 510 cm(-1), the skeletal C-C stretch band intensity at 934 cm(-1), and the content of the secondary structure of the alpha helix were observed. Both S--S linkages and alpha helix structure were important to the stabilization of insulin conformation. Modification of insulin may change the biological activity either by reducing the affinity of the hormone for the receptor or by decreasing the ability of the complex, when formed, to elicit a biological response.     

33 Hz脉冲电场辐照对胰岛素淀粉样变性的影响

蛋白质结构失稳后会发生错误折叠、集聚或纤维化,不仅丧失正常功能,有时甚至会产生生物毒性,导致相关疾病。纤维化了的蛋白质是神经退行性疾病以及二型糖尿病等的主要诱因,它在溶液中具有和淀粉类似的特性,因此蛋白质的纤维化又被称为淀粉样变性。电磁辐射是引起蛋白质结构失稳的一个常见因素。经电场辐照后,蛋白质会发生去折叠和集聚,改变自发折叠机制。同时,经受电场辐照的扰动而失稳的蛋白质,纤维化过程也会受到一定的影响。以胰岛素为研究对象,利用硫磺素T(ThT)染色的荧光光谱法、透射电子显微镜(TEM)以及圆二色谱(CD)法,分别从纤维化的宏观动力学过程、成熟纤维丝微观形貌以及原纤维二级结构组成等不同角度,探究经33 Hz脉冲电场(PEF)不同电场强度及不同持续时间辐照后蛋白质在体外淀粉样变性机制的变化情况。结果表明,胰岛素溶液经过33 Hz PEF辐照后,淀粉样变性初期产生前体蛋白的成核期延长,原纤维丝聚集延长过程(即中间产物的寿命)缩短,形成的成熟纤维丝长度变短且整齐成簇无分支。这些效应随着辐照电场强度和辐照时间的增加而有不同程度的加强。研究结果一致说明PEF辐照对胰岛素的淀粉样变性有一定的抑制作用。     

荧光光谱法研究低频脉冲电场对胰岛素分子的作用

胰岛素作为一种胞间信号分子,对于生命信息的传递起着极为重要的作用。探讨低频脉冲电场对胰岛素分子的作用,对于从细胞信号系统的角度来解释生物电磁效应有着十分重要的意义。在实验中,对照组和场暴露组之间荧光峰值强度的差别表明了低频脉冲电场改变了胰岛素分子的构象,低频脉冲电场可能通过破坏胰岛素分子氢键和重新形成某些氢键来改变它的构象。本文结果表明胞间信号分子也是低频电磁场作用的一个重要靶体。     

Cell deformation and increase of cytotoxicity of anticancer drugsdue to low-intensity transient electromagnetic pulses

In this paper, cell deformation induced by low-intensity electromagnetic pulses (EMPs) is presented. A broad-band transverse electromagnetic wave cell (BTEM cell) was used in the experimental system to simulate the free space transmission condition. The biological samples were exposed to the EMP field in the BTEM cell. After the chick's erythrocytes were exposed to EMP field, pores on their membranes were observed by a scanning electron microscope. Cell fusion was also found between the chick's erythrocytes as well as between the rabbit's. In other experiments, it is found that the EMP field can increase the cytotoxicity of some anticancer drugs. The results suggest that the membrane deformation is a secondary effect of electromagnetic fields     

强磁场下ITER垂直稳定性线圈的电磁性能研究

垂直稳定性线圈是ITER托卡马克装置中用以维持等离子体垂直稳定性的核心部件,然而该线圈处于强磁环境下,一旦线圈励磁运行以后,线圈电流与外部背景场交互作用激发的电磁载荷将会对线圈产生强烈的电磁冲击.为了分析稳态和瞬态电磁载荷对线圈结构的影响,首先采用电流丝等效模型并基于椭圆积分计算了背景场线圈和等离子体电流的磁场,以及极端运行状态下背景场所诱发的电磁力.在电磁计算的基础上,创建循环对称磁-结构耦合分析模型并采用间接耦合法,将电磁力密度以载荷边界条件插值到结构分析模型,计算评估线圈在稳态电磁载荷下的力学性能.此外,针对脉冲电流引起的电磁疲劳,采用ASME主应力方向恒定的疲劳设计规范,结合Goodman修正法并以无限次循环条件下材料应力强度为评定标准,对线圈各组件的应力进行了评定,结果表明线圈各组件均有足够的安全裕度.该分析方法可为托卡马克其它磁体线圈的电磁性能评估提供参考.     

Pressure induced quantum critical point and non-fermi-liquid behavior in BaVS3

We report on experiments giving evidence for quantum effects of electromagnetic flux in barium alumosilicate glass. In contrast to expectation, below 100 mK the dielectric response becomes sensitive to magnetic fields. The experimental findings include both lifting of the dielectric saturation by weak magnetic fields and oscillations of the dielectric response in the low temperature resonant regime. As the origin of these effects we suggest that the magnetic induction field violates the time reversal invariance leading to a flux periodicity in the energy levels of tunneling systems. At low temperatures, this effect is strongly enhanced by the interaction between tunneling systems and thus becomes measurable.     

极低频电磁场曝露对于大鼠敏感组织红外光谱特征的影响

极低频电磁场非热生物效应的发生与生物组织接受电磁辐射后微观结构的改变有关,利用红外光谱学分析方法可以有效的研究电磁辐射生物效应发生的微观机制。研究了极低频电磁场曝露对于大鼠电磁敏感组织红外光谱特征的影响,对曝露于50 Hz,0.75 mT极低频电磁场作用20天的大鼠的血液、脑和睾丸组织的红外光谱与正常大鼠组织的红外光谱进行比较分析,从分子水平阐述了极低频电磁场曝露作用生物效应的发生机制。实验结果表明极低频电磁场曝露可导致大鼠敏感组织某些特征吸收峰峰位和峰强产生了规律性的变化,说明傅里叶变换红外光谱方法是研究电磁场不同生物效应的发生机制的一种有效手段。     

Reduction of RF-induced sample heating with a scroll coil resonator structure for solid-state NMR probes

Heating due to high power 1H decoupling limits the experimental lifetime of protein samples for solid-state NMR (SSNMR). Sample deterioration can be minimized by lowering the experimental salt concentration, temperature or decoupling fields; however, these approaches may compromise biological relevance and/or spectroscopic resolution and sensitivity. The desire to apply sophisticated multiple pulse experiments to proteins therefore motivates the development of probes that utilize the RF power more efficiently to generate a high ratio of magnetic to electric field in the sample. Here a novel scroll coil resonator structure is presented and compared to a traditional solenoid. The scroll coil is demonstrated to be more tolerant of high sample salt concentrations and cause less RF-induced sample heating. With it, the viable experimental lifetime of a microcrystalline ubiquitin sample has been extended by more than an order of magnitude. The higher B1 homogeneity and permissible decoupling fields enhance polarization transfer efficiency in 15N-13C correlation experiments employed for protein chemical shift assignments and structure determination.     

跑道线圈换能器在铁路重载货车探伤中的应用*

针对在线车轮超声探伤系统的工程应用,研究了跑道线圈电磁超声换能器由洛伦兹力换能机制在钢中产生的辐射声场。根据外磁场和线圈配置,将表面力源近似为非均匀的水平剪切力源,数值计算得到了此力源的辐射声场指向性图,并与实验结果进行比对,结果表明辐射的水平偏振横波具有中间强两侧弱的指向性,对理解跑道形电磁线圈超声换能器的辐射声场和在重载货车车轮辋裂缺陷探伤中的工程应用具有一定的指导意义。     

An Analog of the Kubo formula for conductivity of spatially inhomogeneous media in spatially inhomogeneous electric fields

The average densities of currents and charges induced by a weak electromagnetic field in spatially inhomogeneous systems at a finite temperature are calculated. The Kubo formula for the electrical conductivity tensor is generalized to spatially inhomogeneous systems and spatially inhomogeneous fields. The contributions containing electric fields and derivatives of the fields with respect to coordinates are separated. It is shown that semiconductor quantum wells, wires, and dots can be treated as spatially inhomogeneous systems.