The hybridization of two complementary ssDNA is essential for molecular biology and biological physics. T7 ssDNA binding protein (gp2.5) can rapidly facilitate this hybridization, but the mechanism and kinetic process remain unknown. As determined by fluorescence resonance energy transfer (FRET) and rapid kinetic analysis methods, gp2.5 binding coiling ssDNA to form gp2.5-ssDNA complex is the rate-limiting step for the entire DNA hybridization process. Afterward, the hybridization initiates from either the terminus or the internal part of ssDNA at a nucleation rate of 0.45 s⁻¹. The remaining DNA strands are hybridized in a zippering mode at a rate of 0.07 s⁻¹, limited by the dissociation of gp2.5 from ssDNA. The gp2.5-faciliated hybridization rate constant (74 μM⁻¹s⁻¹) is much higher than the spontaneous hybridization rate (1.7 μM⁻¹s⁻¹) in the absence of gp2.5. These hybridization mechanism and kinetic process are different from those by other ssDNA binding proteins, such as T4 gp32, Escherichia coli SSB protein and recA protein. Compare with E. coli SSB, the relatively slower association of gp2.5 to ssDNA and faster dissociation of gp2.5 from ssDNA are probably the major reasons to facilitate the rapid hybridization. This study provides valuable insights into the molecular mechanism of the recombination and repair processes and proposes a basis for improvement in their associated biotechnologies.

两个互补的ssDNA的杂交对于分子生物学和生物物理学至关重要。T7 ssDNA结合蛋白（gp2.5）可以快速促进这种杂交，但机理和动力学过程仍然未知。通过荧光共振能量转移（FRET）和快速动力学分析方法确定，gp2.5结合缠绕的ssDNA形成gp2.5-ssDNA复合物是整个DNA杂交过程的限速步骤。之后，杂交以0.45 s ^-1的成核速率从ssDNA的末端或内部开始。剩余的DNA链以拉链形式以0.07 s ^-1的速率杂交，受gp2.5从ssDNA的解离的限制。gp2.5促进的杂交速率常数（74μM- ¹s ^-1）比没有gp2.5时的自发杂交率（1.7μM ^-1 s ^-1）高得多。这些杂交机制和动力学过程不同于其他ssDNA结合蛋白，例如T4 gp32，大肠杆菌SSB蛋白和recA蛋白。与大肠杆菌SSB相比，gp2.5与ssDNA的相对较慢的结合以及gp2.5与ssDNA的较快速的解离可能是促进快速杂交的主要原因。这项研究为重组和修复过程的分子机制提供了宝贵的见识，并为改进其相关的生物技术提供了基础。