菌紫质LB膜时空信号响应模型及方向检测效应的研究

在测量和分析了菌紫质ＬＢ膜的时空信号响应的基础上,提出了菌紫质ＬＢ膜的时空信号响应模型。并用菌紫质ＬＢ膜的时空信号响应模型。并用菌紫质ＬＢ膜的这些特性设计了能检测“对比边”运动方向、角度和转速的方法。     

光电响应对紫膜外表面[k~+]依赖性与质子泵效率相关

本文研究发现,不锈钢／电沉积紫膜薄膜／含水胶（电介质）／铜型菌紫质光电池的光电响应对紫膜外表面的钾离子浓度的依赖性与质子泵效率的这种依赖性成相关性。这种相关性说明：１．膜中菌紫质的光电响应主要来自质子泵运而非钾离子直接的贡献;２．存在一合适的离子浓度使菌紫质的光电响应有极大值;３．作用在外表面的离子主要影响质子释放结构域     

菌紫质LB膜时空信号响应模型及方向检测效应的研究

在测量和分析了菌紫质ＬＢ膜的时空信号响应的基础上,提出了菌紫质ＬＢ膜的时空信号响应模型。并用菌紫质ＬＢ膜的这些特性设计了能检测“对比边”运动方向、角度和转速的方法。     

光电响应对紫膜外表面[k~ ]依赖性与质子泵效率相关

本文研究发现,不锈钢／电沉积紫膜薄膜／含水胶（电介质）／铜型菌紫质光电池的光电响应对紫膜外表面的钾离子浓度的依赖性与质子泵效率的这种依赖性成相关性。这种相关性说明：１．膜中菌紫质的光电响应主要来自质子泵运而非钾离子直接的贡献;２．存在一合适的离子浓度使菌紫质的光电响应有极大值;３．作用在外表面的离子主要影响质子释放结构域     

湿度和温度对酰化紫膜LB膜M衰减的影响

用闪光动力学光谱仪测量了酰化紫膜ＬＢ膜中Ｍ衰减速率的变化。酰化紫膜ＬＢ膜的衰减无论是悬浮液状态,还是ＬＢ膜中,均比未修饰的要慢。在温度为２０℃时,酰化紫膜ＬＢ随着相对湿度的增加,Ｍ衰减加快。在相对湿度较低时（ＲＨ３４—７５％）,变化较平缓,即Ｍ的衰减加快不明显;在相对湿度较高时（ＲＨ８４—９５％）,Ｍ衰减明显加快。温度的变化则随相对湿度不同而不同。相对湿度较低时,随着温度的升高,Ｍ衰减加快;相对湿度较高时,Ｍ衰减反而减慢。酰化紫膜悬浮液的Ｍ衰减随着温度的升高而明显加快．这说明酰化紫膜ＬＢ膜中ＢＲ水合程度可能是直接影响Ｍ衰减的因素之一。     

表面活性剂CHAPS对紫膜脂双层微环境的作用

利用顺磁性自旋标记技术,探测在表面活性剂ＣＨＡＰＳ（３－〔（３－Ｃｈｏｌａｍｉｄｏｐｒｏｐｙｌ）ｄｉｍｅｔｈｙｌ－ａｍｍｏｎｉｏ〕ｐｒｏｐａｎｅｓｕｌｆｏｎｉｃ ａｃｉｄ）作用下,紫膜脂双层微环境的物理参数（序参数Ｓ和旋转相关不同。表层序参数Ｓ值随ＣＨＡＰＳ浓度的增加而逐渐减小;深层旋转相关时间τｃ值开始随ＣＨＡＰＳ浓度的增加而增大,在ＣＨＡＰＳ浓度为５ｍｍｏｌ／Ｌ时,τｃ值呈现最大值,随着ＣＨＡ     

紫膜BLM的光电位与非质子离子迁移

嵌入紫膜碎片的BLM系统在不同离子强度的介质中产生不同的光电位信号。本文通过在介质中加入离子载体或离子通道剂对紫膜的光电响应信号进行了系统的研究。结果表明:上述光电位信号的差异主要是由紫膜的非质子离子的迁移引起的。与紫膜的质子跨膜迁移相比,这种非质子离子迁移也是由光驱动的,随介质的离子强度的增强而显著增强,但它的迁移速率更快,且产生反向的光电位。用通常方法所获得的光电位信号主要是这两种迁移信号的迭加。三价阳离子(La~(3+))可使紫膜质子泵反向并能抑制质子的吸收,但它似乎并不参与紫膜的非质子离子迁移。     

用菌紫质Langmuir—Blodgett膜模拟视网膜神经节细胞感受野的DOG滤波等特性

用菌紫质ＬＢ（Ｌａｎｇｍｕｉｒ—Ｂｌｏｄｇｅｔｔ）膜以一维形式模拟了视网膜神经节细胞的ＯＮ－中心型感受野。实验表明菌紫质ＬＢ膜具有ＯＮ型和ＯＦＦ型微分响应特性。对运动狭缝,所模拟的人工视网膜感受野的周边区和中心区都具有类高斯函数形式的滤波特性,整个人工视网膜感受野具有与高等动物视网膜相似的ＤＯＧ（ＤｉｆｆｅｒｅｎｃｅｏｆＧａｕｓｓｉａｎｓ）滤波运算功能。     

紫膜在含水凝胶中的定向和状态

用几种光谱学方法研究了紫膜凝胶的定向度、生色团视黄醛的状态以及其光循环中间产物M的动力学过程。结果表明:用通常采用的制备方法所得到的紫膜凝胶虽然能得到光电响应信号,但其定向度并不理想,生色团视黄醛的构象受到较大扰动,光循环中间产物M的产出及衰减也受到抑制,部分样品甚至由于其视黄醛的脱落而完全失去颜色,其质子泵功能也随之丧失。这说明虽然紫膜凝胶是目前研究紫膜质子泵机理(光电响应测量)和构造分子电子器件较好的和有希望的人工膜系统之一,但由于该系统对紫膜结构和功能的扰动仍然较大,紫膜的定向较难控制,所以,我们仍需在凝胶的形成体系及方法的改进上作大量工作。     

10眼菌紫质光感受器及其对运动边的检测

铜（或不锈钢）／保护膜／紫膜薄膜／氧化铟锡型菌紫质光电池（有时也叫做光感受器）具有微分光电流特性和方波型光电压特性。用该种光电池仿昆虫复眼的小眼结构构制了１０眼菌紫质光感受器,用其模拟动物神经节细胞的ＯＮ中心感受野并用于运动边的检测     

Characteristics and mechanisms of the two types of photoelectric differential response of bacteriorhodopsin-based photocell

Bacteriorhodopsin (BR)-based photocells have been assigned possessing differential photoelectric response. But recently we found that the differential response described before, which occurred in milliseconds to seconds, outputting a positive pulse when light was on and a negative pulse when light was off, was not the intrinsic property of the BR molecule. It was partially caused by the measuring circuit. By measuring the photoelectric response signal of the BR film photocell to a short laser pulse, the impulse response function of the BR film photocell was obtained by data fitting with MATLAB software. A simulation system was accordingly developed. The output response signals of the BR film photocell under different stepping incident light were calculated. By simulation and analysis, it was concluded that the differential response caused by the intrinsic property of the BR molecule happened in microseconds time scale, and it produced a negative pulse when light was on and a positive pulse when light was off. It was much faster but much weaker than that described before.     

A PHOTOELECTRIC DENSITOMETER FOR USE WITH SUSPENSIONS

A device for quickly and accurately measuring the population density of a suspension of microorganisms, permitting the preparation of yeast suspensions of known density to within 1 per cent error, was constructed with two Visitron photoelectric cells, a single light of high intensity and a good Wheatstone bridge for balancing the currents from the two photoelectric cells. A large Pyrex milk culture tube holding the suspension is placed in the path of one beam of light coming through a small longitudinal slit and thence to one photocell; a second similar slit directs another beam of light upon the second photocell, thus causing dissimilar currents to flow, the ratio of whose magnitudes may be measured by the bridge resistances. A relation between these currents and the relative light intensities is shown, and the one significant unmeasurable variable (the characteristic constant of a photocell) is practically eliminated by the use of a method of ratios. After careful standardization of technique the apparatus proved more accurate than other methods available for the purpose indicated. In rapid use its accuracy may be put safely at 1 per cent for measuring the densities of cultures of approximately the same age and composed of cells having comparable optical characteristics.     

铁/紫膜/胶/铜光电池在光触发瞬时的界面电势研究

在分析菌紫质光驱质子泵过程的基础上 ,应用Hong的化学电容的概念 ,提出在菌紫质人工膜系统中等效存在C -电容和N -电容 ,并由此研究了铁/紫膜/胶/铜光电池在光触发瞬时的界面电势。结果可提供于以菌紫质为基础的分子电子器件 ,和菌紫质光驱质子泵机理的研究。     

电极介导的菌紫质干膜微分光电流响应的整流性质

在长方形光脉冲光照下,菌紫质(bacteriorhodopsin,BR)干膜组装成夹层光电池具有微分光电流响应．在氧化铟锡(ITO)导电玻璃/BR膜/封口膜/不锈钢形成的干膜电池下可观察到整流特性,而在不锈钢/BR膜/封口膜/ITO导电玻璃形成的干膜电池下则观察不到整流特性,这说明是电极介导的整流．平衡电压测定表明：工作电极/BR膜表面与对电极/BR膜表面有不同的性质,电极的界面效应控制了BR的取向．酸与碱产生的瞬间电流极性也证实了电极整流行为的存在．这些结果将有助于了解BR膜的微分光电响应．     

缬氨霉素对紫膜碎片双层平板脂膜(BLM)光电响应的影响

本实验中测量了缬氨霉素对双层平板膜系统的电性质和紫膜碎片BLM上光电响应的作用.实验结果表明:缬氨霉素对K~+很灵敏,它可使大豆磷脂BLM的膜电阻下降近四个量级,膜的稳定性也下降.它对Na~+也有作用,但其作用不如K~+那么明显.在缬氨霉素作用下,K~+对紫膜碎片BLM光电响应的影响十分明显,它可以使光电压完全消失.Na~+对紫膜碎片BLM的作用则比K~+的作用小得多.     

Bacteriorhodopsin-mediated photoelectric responses in lipid/water systems

Summary Bacteriorhodopsin-mediated photopotential generation has been studied in two kinds of lipid/water systems: (1) decane solution of asolectin was used as the lipid phase; (2) a mixture of bacteriorhodopsin sheets and hexane solution of phosphatidyl choline was applied onto a water surface to form a monolayer, and then the monolayer was covered with a 0.3-mm decane layer. In both cases, illumination was found to induce formation of an electric potential difference, with the bulk water phase being found negative when measured with a vibrating electrode. In the latter, but not in the former, system small amounts of a protonophorous uncoupler were found to stimulate the photoresponse. Large amounts of the uncoupler proved depressing in both systems. Phenyldicarbaundecaborane anion (PCB^–) was shown to substitute for the uncoupler, being much more potent both as an activator and as an inhibitor of the photoresponse. In both studied systems, gramicidin A inhibits the photoresponse, the effect being greatly potentiated by K⁺, Na⁺ or H⁺ ions.In the system decane solution of asolectin/water, an Ag/AgCl electrode immersed into the lipid phase can be used instead of a vibrating electrode. All the measured features of the photoelectric responses observed with any of these electrodes were found to be quite similar to those inherent in a phospholipid-impregnated collodion film adsorbing bacteriorhodopsin sheets on one of its surfaces.A scheme is discussed built on the assumption that photopotentials in all the studied systems are due to an uphill light-dependent transport of H⁺ ions from the bulk water phase to a water cavity localized between a bacteriorhodopsin sheet and the surface of the bulk lipid phase. Thus, the above lipid/water systems containing bacteriorhodopsin are composed of four, rather than two, phases, as was supposed previously.Bacteriorhodopsin-mediated photopotential generation has been studied also in the decane/water system without phospholipids. This system with bacteriorhodopsin sheets added to the water phase demonstrates a light-dependent photoelectric response reaching 1.5 V, which can be measured only by a vibrating electrode. The photoresponse starts after a lag period of several seconds. Switching off the light results in the reversal of the light-induced electric potential change. The off-effect also has a lag period. The action spectrum of the photoresponse shows at least two maxima: a smaller at 560 nm and a larger at <420 nm. Free retinal can substitute for bacteriorhodopsin in the studied system. All the above effects disappear if, instead of air, argon is used. In the system decane solution of asolectin/water, a slow photoelectric response of this type can be demonstrated at neutral pH in the presence of gramicidin and at pH 4 without gramicidin. A suggestion is put forward that the slow photoelectric response is due to an interface Volta-potential change induced by a product of photooxidation of bacteriorhodopsin and/or free retinal released from bacteriorhodopsin.     

外加电场对平板膜(BLM)中单体菌紫质分子bR光电响应的影响

本文研究了外加电场对单体菌紫质分子在平板膜系统中光电响应的影响.外加正电场时(外池为正,内池为负),光电响应信号变小,电场加至+52mV时,光电响应信号极性发生反转.外加负电场时,光电响应信号增大.本文提出了极性发生反转的可能模型,并对其机理进行了初步探讨.     

两种化学修饰菌紫质的光化循环和光电位

本文分别用两种氮氧自由基对菌紫质(bR)中的两种氨基酸残基——赖氨酸和丝氨酸进行了修饰,并对修饰后的bR光循环中间产物M_(412)动力学过程、质子泵效率及光电响应信号进行了测量。通过与正常紫膜进行比较,可以看出:赖氨酸被修饰后,M_(412)快、慢组分的衰减及质子的吸收过程均减慢,M_(412)和质子的产额、跨膜光电位信号均有不同程度的提高;丝氨酸被修饰后,M_(412)和质子的动力学过程的变化与赖氨酸基本相同,但M_(412)和质子的产额及跨膜光电位提高很大,且光电位出现缓慢反向现象。结果表明赖氨酸不大可能直接参与质子的传递过程,其对紫膜质子泵的影响主要是通过其所带电荷对表面电位的贡献;而丝氨酸却似乎对bR的功能影响很大并对维持质子通道构象环境的稳定起着很大作用。     

细菌视紫红质的两种光电微分响应及其机制

利用MATLAB软件对细菌视紫红质 (BR)膜光电器件的脉冲响应实验数据进行拟合 ,得到器件的冲激响应函数。据此用SIMULINK模块构造出了反映BR光电器件特性的仿真系统。利用此系统对不同间断光入射BR光电器件时的输出响应信号进行了仿真计算。通过分析得出结论 :以前所描述的微分响应 (发生在毫秒到秒的时间量级 ,在光打开时产生一个正脉冲 ,在光关掉时产生一个负脉冲 )并非BR分子固有的特性 ,部分是由于测量电路引起的。BR分子本身特性引起的微分响应是发生在微秒时间量级 ,而且在光打开时产生一个负脉冲 ,在光关掉时产生一个正脉冲。对这两种微分响应产生的机制分别进行了探讨     

pH梯度对平板膜中单体菌紫质分子光电响应的影响

利用重组技术把单体bR包入DMPC脂质囊泡中,通过吸收光谱和圆二色谱的测定,证明bR在囊泡中仍以单体存在。同时测定了外界pH梯度对单体bR脂质囊泡BLM光电响应的影响,观察到pH值当内池大于外池其差值超过2时就可产生光电响应信号极性的反转,并对此结果作了一定的讨论。