Choi Young Shin, Cho Tae-Sub, Kim Jong Moon, Han Sung Wook, Kim Seog K
Department of Chemistry, Yeungnam University, Gyeongsan City, Gyeong-buk, 712-749, Republic of Korea.
Biophys Chem. 2006 May 20;121(2):142-9. doi: 10.1016/j.bpc.2006.01.005. Epub 2006 Feb 3.
Fluorescence characteristics of Hoechst 33258 bound to G-6 dendrimer, to the DNA-G-6 dendrimer complex, and to DNA were compared with that in an aqueous solution. The spectral properties including fluorescence emission spectrum, accessibility of anionic quencher, as well as the fluorescence decay time of the Hoechst 33258 are different for all three conditions, indicating that the environments in these conditions are different. Close analysis of the fluorescence properties led us to suggest that Hoechst 33258 located at or near the contact area of the dendrimer and DNA in the DNA-G-6 complex. In the complex, in the absence of Hoechst 33258, the shape of the circular dichroism in the DNA absorption region remained, indicating that DNA is in B form in the complex. On the other hand, the magnitude of linear dichroism (LD) decreased upon DNA-G-6 dendrimer complex formation. The decrease in LD magnitude reflects the shortening of the DNA contour length, which is expected from the fact that a large part of linear DNA is required to wrap the surface of G-6 dendrimer.
将与G-6树枝状大分子结合的、与DNA-G-6树枝状大分子复合物结合的以及与DNA结合的Hoechst 33258的荧光特性与在水溶液中的荧光特性进行了比较。对于所有这三种情况，包括荧光发射光谱、阴离子猝灭剂的可及性以及Hoechst 33258的荧光衰减时间在内的光谱性质均不相同，这表明这些情况下的环境不同。对荧光性质的仔细分析使我们推测，在DNA-G-6复合物中，Hoechst 33258位于树枝状大分子与DNA的接触区域处或附近。在该复合物中，在没有Hoechst 33258的情况下，DNA吸收区域的圆二色性形状保持不变，这表明复合物中的DNA呈B型。另一方面，在形成DNA-G-6树枝状大分子复合物后，线性二色性（LD）的大小降低。LD大小的降低反映了DNA轮廓长度的缩短，这是由以下事实所预期的：需要很大一部分线性DNA来包裹G-6树枝状大分子的表面。
