STRUCTURE AND INTERACTIONS OF DNA

本研究的远期目标是评估 与选定的非螺旋相关的热力学特性 和DNA的异常结构，有些可能提供特异性， 用于吸引酶进行复制、转录等。 引起不同模式的力的定量评价 DNA中的动态行为应该有助于解释 非编码区序列的微小变化的基因表达， 以及DNA序列的进化。 近期目标是 来测量中断螺旋的能量成本， 维持非螺旋环结构，包括剪切力 需要在内部较短的长度上分离相对的链 螺旋的延伸。 最初的目的是形成循环 样品是寡聚体（A度T）N的短长度，其中50 比N大于10 bp，夹在稳定的边界之间， （G摄氏度）40-80度。 样本将被合成为 在pBR 322的Pst I位点中的重组体，并切下用于 物理研究。 热力学特性应 从螺旋-非螺旋平衡的观察中提取 通过在几个波长下的高分辨率光学熔化监测 同时采用数字差分近似法。 以后的研究将讨论环形成的问题， 不同碱基组成和序列特征的结构域。 在一项相关研究中， 这十个独特的堆叠相互作用将从 稳定性的具体的，充分表征的结构域产生的 pBR 322的多转变熔解曲线。 最近邻 与十个稳定常数相关的频率将 被分配给特定的子转换，这些子转换通过 当负责熔化温度的结构域发生变化时， 通过限制性内切酶切割亚转换。 在另一项研究中， 1399 bp的卫星I和46 bp的卫星I的变异将被确定。 牛基因组的卫星II重复序列。 序列 这些卫星的变化将从增加的 在种群亚跃迁的温度范围内 重复序列的数量超过了单个克隆样本。

The distant objectives of this study are the evaluations of thermodynamic characteristics associated with selected nonhelical and aberrant structures of DNA, some that may provide specificity for the attraction of enzymes for replication, transcription, etc. Quantitative appreciation of the forces that induce different modes of dynamic behavior in DNA should help explain subtle effects on gene expression of small changes in sequence in noncoding regions, as well as the evolution of DNA sequences. The near-term goal is to measure the energetic costs of interrupting the helix and maintaining nonhelical loop structures, including the shear forces needed to separate opposing chains over short lengths in internal stretches of helix. Initially it is intended that the loop forming specimen be short lengths of oligo(A degrees T) N, where 50 greater than N greater than 10 bp, sandwiched between stable boundaries of (G degrees C) 40-80 degrees. The specimen will be synthesized as a recombinant in the Pst I site of pBR322 and excised for the physical studies. Thermodynamic characteristics are to be extracted from observations of the helix-nonhelix equilibrium monitored by high resolution optical melting at several wavelengths simultaneously by the digital-difference approximation method. Later studies will take up the question of loop formation in domains of different base compositions and sequence features. In a correlated study the thermodynamics associated with each of the ten unique stacking interactions will be evaluated from the stabilities of specific, well characterized domains producing the multitransitional melting curve of pBR322. Nearest neighbor frequencies, to which the ten stability constants are related, will be assigned to specific subtransitions that reveal themselves by changes in melting temperature when the domains responsible for the subtransitions are cut by restriction enzymes. In a separate study, the precise amounts and level of sequence variation will be determined for the 1399bp satellite I and 46bp satellite II repetitive sequences from the bovine genome. Sequence variations in these satellites will be determined from the increase in the range of temperature of the subtransition for the population of repetitive sequences over that of single cloned specimens.