Vibrational CD (VCD) and atomic force microscopy (AFM) study of DNA interaction with Cr3+ ions:: VCD and AFM evidence of DNA condensation
Vibrational CD (VCD) and atomic force microscopy (AFM) study of DNA interaction with Cr3+ ions:: VCD and AFM evidence of DNA condensation
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DOI：
10.1002/bip.10159
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发表时间：
2001-01-01
期刊：
影响因子：
2.9
通讯作者：
Wieser, H
中科院分区：
文献类型：
--
作者：
Andrushchenko, V;Leonenko, Z;Wieser, H
用振动圆二色谱（VCD）、红外吸收光谱（IR）和原子力显微镜（AFM）研究了室温下天然小牛胸腺DNA与Cr ~（3+）的相互作用。以Cr ~（3+）离子结合为主。N-7（G）和磷酸基团。观察到类似于电子CD（ECD）光谱的PSI型VCD光谱，其出现在PSI型DNA缩合过程中。这些光谱的特点主要是异常的，几倍的VCD强度增加。这种异常的VCD光谱被分配到DNA凝聚与形成的大而致密的粒子的大小相媲美的探测红外光束的波长，并拥有大规模的螺旋。原子力显微镜证实了由Cr 3+离子和形成的紧密的DNA颗粒负责的PSI型VCD光谱的DNA缩合。在增加的Cr 3+离子浓度的冷凝物的形状从松散的花状，结构高度填充致密的球体。即使在研究的最高浓度的Cr 3+离子下也没有看到DNA变性。DNA的二级结构还在吗？在冷凝前后的B型。VCD和IR以及AFM被证明是研究DNA缩合的有效组合。除了VCD确定DNA凝聚的能力之外，VCD和IR可以在同一实验中提供关于凝聚颗粒中所含DNA的二级结构的明确信息。(C)2002 Wiley Periodicals，Inc.
The interaction of natural calf thymus DNA with Cr3+ ions was studied at room temperature by means of vibrational CD (VCD) and infrared absorption (ir) spectroscopy, and atomic force microscopy (AFM). Cr3+ ion binding mainly. to N-7 (G) and to phosphate groups it-as demonstrated. psi-Type VCD spectra resembling electronic CD (ECD) spectra, which appear during psi-type DNA condensation, were observed. These spectra are characterized mainly by an anomalous, severalfold increase of VCD intensity. Such anomalous VCD spectra were assigned to DNA condensation with formation of large and dense particles of a size comparable to the wavelength of the probing ir beam and possessing large-scale helicity. Atomic force microscopy confirmed DNA condensation by Cr3+ ions and the formation of tight DNA particles responsible for the psi-type VCD spectra. Upon increasing the Cr3+ ion concentration the shape of the condensates changed from loose flower-like, structures to highly packed dense spheres. No DNA denaturation was seen even at the highest concentration of Cr3+ ions studied. The secondary structure of DNA remained it? a B-form before and after the condensation. VCD and ir as well as AFM proved to be an effective combination for investigating DNA condensation. In addition to the ability of VCD to determine DNA condensation, VCD and ir can in the same experiment provide unambiguous information about the secondary, structure of DNA contained in the condensed particles. (C) 2002 Wiley Periodicals, Inc.