STRUCTURE AND INTERACTIONS OF DNA

这项研究的遥远目标是对 与选定的非螺旋相关联的热力学特性 以及DNA的异常结构，其中一些可能提供了特异性 用于吸引酶进行复制、转录等。 对导致不同模式的力量的量化评价 DNA中动态行为的研究应该有助于解释 非编码区序列微小变化的基因表达， 以及DNA序列的进化。近期目标是 为了测量打断螺旋的能量成本和 维护非螺旋环状结构，包括剪切力 需要在内部以较短的长度分隔相对的链 伸展的螺旋。最初的意图是形成环路 样品为较短长度的寡聚(A度T)N，其中大于50 大于N大于10个BP，夹在稳定边界之间 (G℃)40-80度。标本将被合成为 PBR322的Pst I位点的重组体，并被切除用于 物理研究。热力学特性将是 从螺旋-非螺旋平衡的观测中摘录 由多个波长的高分辨率光学熔化监测 同时采用数值差分逼近法。 稍后的研究将在#年讨论环路形成的问题 具有不同碱基组成和序列特征的结构域。 在一项相互关联的研究中，与每一个 十种独特的堆叠交互作用将从以下方面进行评估 特定的、特征良好的区域的稳定性 PBR322的多相变熔融曲线。最近的邻居 与这十个稳定常量相关的频率将 被分配给特定的子转变，这些子转变通过以下方式揭示自己 熔化温度的变化 亚转换被限制性内切酶切割。 在另一项研究中，序列的精确数量和水平 将确定1399个碱基的卫星I和46个碱基的变异 来自牛基因组的卫星II重复序列。数列 这些卫星的变化将从增加的数量中确定 在人口次转变的温度范围内 重复序列的数量超过了单个克隆样本的数量。

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.