A Velocity-Gradient Flow Cell for Raman and Emission Spectroscopy of a DNA-Drug Solution

这项工作的目的是构建一种新的仪器，用它可以检查溶液中dna -药物复合物的几何形状。在普通溶液中，分子是随机取向的。因此，在对这种溶液进行光谱测量时，有关分子各向异性特性的信息是模糊的。因此，分子在溶液中取向是可取的。这对于DNA双链来说是可能的，只要将其溶液置于速度梯度为10^3 cm s^<-1>/cm数量级的流体中。Wada和Kozawa (j .高分子材料科学。，A2, 853(1964))，例如，在放置在两个同轴圆柱体之间的间隙中的溶液流动中产生这样的速度梯度，其中一个圆柱体快速旋转。他们检测了260 nm DNA吸收的各向异性。在本研究中，类似的技术已应用于拉曼和荧光光谱。将DNA溶液放置在两个同轴圆柱体之间的空隙（1mm）中；外筒内径为12mm，内筒外径为10mm。当内筒以每分钟2500转的速度旋转时，在间隙处产生足够大的液体流动速度梯度，从而使DNA分子沿流动方向定向。DNA分子拉曼散射的各向异性是通过从圆柱体底部平行于圆柱体轴线的方向将激发激光束射入间隙来检测的。在DNA溶液中加入抗肿瘤药物阿克拉霉素A （HCl盐），并检测其发射光谱和拉曼光谱的各向异性。已经确定阿克拉霉素与DNA结合时，其发色团方向平行于DNA双链的基面。因此，新构建的仪器被证明是强大的阐明dna -药物相互作用的几何结构。

The purpose of this work is to construct a new instrument with which one can examine the geometry of a DNA-Drug complex in a solution.In ordinary solutions, the molecules are randomly oriented. In a spectroscopic measurement on such a solution, therefore, information on the anisotropic properties of the molecules in question is obscured. Thus it is desirable to have molecules oriented in solution. This is known to be possible for the DNA duplex by placing its solution in a flow with a velocity gradient of 10^3 cm s^<-1>/cm order of magnitude. Wada and Kozawa (J.Polymer Sci.,A2, 853 (1964)), for example, produced such a velocity gradient in the flow of solution placed in the gap between two coaxial cylinders, one of which was rapidly rotated. They examined the anisotropy of the 260 nm absorption of DNA In the present study, a similar technique has been applied to Raman and fluorescence spectroscopy.A DNA solution was placed in the gap (1 mm) between two coaxial cylinders; the inside diameter of the outer cylinder was 12 mm, and the outside diameter of the inner cylinder was 10 mm. When the inside cylinder was rotated at 2500 revolutions per minute, a sufficiently large velocity gradient of the liquid flow was produced across the gap so that the DNA molecules were oriented along the flow direction. Anisotropy of the Raman scatterings of the DNA molecule was examined by passing an exciting laser beam into the gap from the bottom of the cylinder in the direction parallel to the cylinder axis. An antitumor drug, aclacinomycin A (HCl salt), was added to the DNA solution, and the anisotropy of its emission and Raman spectra was also examined. It has been established that aclacinomycin binds to DNA with its chromophore oriented parallel to the base plane of the DNA duplex.Thus, the newly constructed instrument proved to be powerful for elucidating the geometry of a DNA-drug interaction.