Kuil M E, van Mourik F, Burger W, van Grondelle R
Department of Biophysics, Free University, Amsterdam, The Netherlands.
Biophys Chem. 1988 Dec;32(2-3):211-27. doi: 10.1016/0301-4622(88)87008-x.
The hydrodynamic properties of large homodisperse single stranded DNAs complexed with the helix destabilizing protein of phage T4, the product of gene 32 (GP32), have been measured. The results suggest a size of the binding site between 8 and 10 nucleotides/GP32 molecule, in reasonable agreement with earlier work on a complex between GP32 and single stranded 145 base DNA. From static light scattering experiments it is concluded that the persistence length of these complexes is about 30 nm, distinctly smaller than the generally accepted value for double stranded DNA. The quasi-elastic light scattering properties of the DNA-GP32 complexes were determined. The variation of the apparent translation diffusion coefficient Dapp with the scattering vector q was analyzed using the discrete ISMF and Rouse-Zimm models [S.C. Lin et al., Biopolymers 17 (1978) 425]. The model parameters that followed from the fit of Dapp versus q2 and from an extensive global analysis of the actually measured autocorrelation functions agreed with the notion that these DNA-protein complexes are indeed rather flexible. The continuous Soda model [K. Soda, Macromolecules 17 (1984) 2365] could successfully explain the variation of Dapp versus q2, assuming a persistence length of 30 nm and a base-base distance in the complex of 0.44 nm.
已对与噬菌体T4的螺旋不稳定蛋白（基因32产物，GP32）复合的大尺寸单分散单链DNA的流体动力学性质进行了测量。结果表明，每个GP32分子的结合位点大小在8至10个核苷酸之间，这与之前关于GP32与145个碱基的单链DNA复合物的研究结果相当吻合。从静态光散射实验得出，这些复合物的持久长度约为30 nm，明显小于双链DNA普遍接受的值。测定了DNA - GP32复合物的准弹性光散射性质。使用离散的ISMF和Rouse - Zimm模型分析了表观平移扩散系数Dapp随散射矢量q的变化[S.C. Lin等人，《生物聚合物》17 (1978) 425]。通过拟合Dapp与q2以及对实际测量的自相关函数进行广泛的全局分析得出的模型参数，与这些DNA - 蛋白质复合物确实相当灵活的观点一致。连续的Soda模型[K. Soda，《大分子》17 (1984) 2365]可以成功解释Dapp与q2的变化，假设持久长度为30 nm且复合物中碱基对之间的距离为0.44 nm。
