共查询到18条相似文献,搜索用时 107 毫秒
1.
2.
3.
4.
《物理学报》2016,(18)
传统的分子生物学实验方法基本都是系综的方法,测量的信号来自大量的生物分子的平均响应,这不利于得到生物分子的构象转变与功能的动力学细节.另外,很多生物大分子如细胞骨架蛋白、分子马达等在行使功能的时候都会受到或者产生力的作用,传统的实验方法也难于研究生物分子的力学响应.最近20年左右发展起来的单分子操控技术可以实现对单个分子的操控,同时测量单个分子在拉力作用下的力学响应.最为常用的单分子操控技术主要包括光镊、磁镊和原子力显微镜,不同的技术有不同的特点和适用范围.本文对几种常用的单分子操纵技术的特点,包括物理原理、可以施加的力的范围与精度、可以测量的分子长度范围与精度等做一个系统的介绍.另外,单分子操控技术在生物大分子如核糖核酸(DNA),脱氧核糖核酸(RNA)和蛋白质的构象转变,相互作用,以及分子马达的功能机理等方面已经取得的丰富成果也给出概括性的介绍.本文对生物学家系统的了解单分子操控技术和如何应用该技术解决自己的生物问题提供一个有益的参考. 相似文献
5.
改进了单分子横向磁镊装置,可以直接用于观察单个DNA分子的伸长和扭转并随时更换样品池内的溶液,还可以同时操纵多个DNA分子,大大提高实验效率.此方法可以提供01到40pN范围的拉力,足以满足大部分单分子DNA实验的要求.用该装置实时观测到了DNA分子在拉力作用下的伸长以及在旋转磁场作用下的扭转,并成功地观察到了分子马达拉动DNA的动力学过程,从而验证了该装置的实用性.
关键词:
横向磁镊
单分子操纵
DNA拉伸
DNA扭转 相似文献
6.
7.
文章介绍近年来新发展的几种重要的活细胞内单分子荧光成像方法,如转盘式共聚焦显微术、全内反射荧光显微术、荧光共振能量转移技术等。通过介绍它们的原理、特点和在活细胞内单分子行为研究中的应用实例,展示了这些新方法在生命科学领域广阔的应用前景。 相似文献
8.
磁镊是一种高精度的单分子技术,它用磁场对连有生物大分子的超顺磁球产生磁力,通过追踪磁球的位置来测量生物大分子的长度信息.磁镊包括横向磁镊和纵向磁镊.纵向磁镊空间精度高,但昂贵;横向磁镊简单便宜,但由于受其成像原理的限制,一般情况下只能连接较长的DNA等生物大分子,且其空间精度较差,进而限制了其应用范围.为了解决这个问题,本文改进了横向磁镊,用片层光照明的方法使光线主要被磁球散射,从而能够直接观察到吸附在样品槽侧壁上的磁球,这使得测量短连接的底物成为可能.对于实际应用的检测,首先测试了包含270 bp发卡结构的0.5μm双链DNA,用其中发卡结构的"折叠-去折叠"跳变过程证明了改进后的横向磁镊的确可以追踪短DNA等生物大分子.然后,进一步用16μm的λ-DNA检验了实验系统.最后,将新型横向磁镊与普通横向磁镊及纵向磁镊在小力和大力条件下拉伸不同长度DNA的噪声进行了比较,发现改进后的横向磁镊在空间精度上明显优于普通横向磁镊,与纵向磁镊相比也无明显差异.以上结果证明了改进后的横向磁镊的精度优势,并扩展了横向磁镊的应用范围. 相似文献
9.
10.
11.
A magnetic tweezers setup is used to control both the stretching force and the relative linking number DeltaLk of a palindromic DNA molecule. We show here, in absence of divalent ions, that twisting negatively the molecule while stretching it at approximately 1 pN induces the formation of a cruciform DNA structure. Furthermore, once the cruciform DNA structure is formed, the extrusion of several kilo-base pairs of palindromic DNA sequence is directly and reversibly controlled by varying DeltaLk. Indeed the branch point behaves as a nanomechanical gear that links rotation with translation, a feature related to the helicity of DNA. We obtain experimentally a very good linear relationship between the extension of the molecule and DeltaLk. We use then this experiment to obtain a precise measurement of the pitch of B-DNA in solution: 3.61 +/- 0.03 nm/turn. 相似文献
12.
13.
The appearance of microlenses in the amorphous crystal Ge33As12Se33 modulated by the acoustic waves with intensity of 107 W/m2 and frequency of (200–400) MHz is presented. The flexibility of microlens, i.e. the dependence of its focal point in 3D space on the parameters of acoustic wave is studied. Basing on flexibility of microlens, a model of acousto-optical tweezers to stretch the λ-phage WLC DNA molecule is proposed. And then the control process of stretched length of DNA molecule in 3D space of the water (fluid) by calibration of the acoustic frequency is numerically observed and discussed. The obtained results show the possibility to use the acousto-optical tweezers to control the stretched length of WLC DNA molecule with high fineness. 相似文献
14.
Kathy R. Chaurasiya Thayaparan Paramanathan Micah J. McCauley Mark C. Williams 《Physics of life reviews》2010,7(3):299-341
Single molecule force spectroscopy is a powerful method that uses the mechanical properties of DNA to explore DNA interactions. Here we describe how DNA stretching experiments quantitatively characterize the DNA binding of small molecules and proteins. Small molecules exhibit diverse DNA binding modes, including binding into the major and minor grooves and intercalation between base pairs of double-stranded DNA (dsDNA). Histones bind and package dsDNA, while other nuclear proteins such as high mobility group proteins bind to the backbone and bend dsDNA. Single-stranded DNA (ssDNA) binding proteins slide along dsDNA to locate and stabilize ssDNA during replication. Other proteins exhibit binding to both dsDNA and ssDNA. Nucleic acid chaperone proteins can switch rapidly between dsDNA and ssDNA binding modes, while DNA polymerases bind both forms of DNA with high affinity at distinct binding sites at the replication fork. Single molecule force measurements quantitatively characterize these DNA binding mechanisms, elucidating small molecule interactions and protein function. 相似文献
15.
为了维持基因的稳定性,每种生物体都含有一套独特的染色质蛋白来保护脱氧核糖核酸(DNA)的结构,观察染色质蛋白对DNA结构的作用过程和结果,可以帮助人们了解这些蛋白的具体功能和作用机理.硫化叶菌是一种能在高温下存活的古细菌,Sso7d是硫化叶菌的一种染色质蛋白.深入地了解Sso7d和DNA链的相互作用,有助于解释硫化叶菌的DNA为何能在高温环境下保持活性,本文通过原子力显微镜(AFM)和磁镊两种单分子操作手段,研究了Sso7d与DNA的相互作用.AFM的实验结果给出了Sso7d与DNA的作用过程:结合Sso7d后,DNA首先发生弯折,然后出现loop结构,最终DNA会团聚为致密的核结构.利用磁镊装置测量了Sso7d的结合对打开DNA双链的影响,实验结果表明Sso7d的结合导致打开DNA双链的力的增大,经过数据分析,计算出Sso7d与DNA结合的结合能?G=3.1k_BT,平均每5.5个碱基对(bp)结合一个Sso7d,较高的结合密度和较大的结合能,两方面的作用结果,解释了Sso7d能够稳定DNA结构的原因. 相似文献
16.
By using a specialty optical fiber, a series of powerful microparticle manipulation tools, including optical tweezers, a micro-optical hand, and an optical gun, are developed and demonstrated. In this paper,a review of our research activities on the optical manipulation of microparticles is presented. In particular,we will describe a kind of specialty optical fiber designed and fabricated for building optical trapping and manipulating tools. The performances of annular core fiber-based optical tweezers, a multicore fiber-based micro-optical hand, and a coaxial dual waveguide fiber-based optical gun are demonstrated as examples of applications and discussed in detail. The fiber can be used in cell manipulation in life science and drug response in medicine. 相似文献
17.
Optical tweezers have been successfully used in the study of colloid science. In most applications people are concerned with the behaviour of a single particle held in the optical tweezers. Recently, the ability of the optical tweezers to simultaneously hold two particles has been used to determine the stability ratio of colloidal dispersion. This new development stimulates the efforts to explore the characteristics of a two-particle system in the optical tweezers.An infinite spherical potential well has been used to estimate the collision frequency for two particles in the optical trap based on a Monte Carlo simulation. In this article, a more reasonable harmonic potential, commonly accepted for the optical tweezers, is adopted in a Monte Carlo simulation of the collision frequency. The effect of hydrodynamic interaction of particles in the trap is also considered. The simulation results based on this improved model show quantitatively that the collision frequency drops down sharply at first and then decreases slowly as the distance between the two particles increases. The simulation also shows how the collision frequency is related to the stiffness of the optical tweezers. 相似文献