Kissing loop interactions (KLIs) are a common motif that is critical in retroviral dimerization, viroid replication, mRNA, and riboswitches. In addition, KLIs are currently used in a variety of biotechnology applications, such as in aptamer sensors, RNA scaffolds and to stabilize vaccines for therapeutics. Here we describe the thermodynamics of a basic intramolecular DNA capable of engaging in a KLI, consisting of two hairpins connected by a flexible linker. Each hairpin loop has a five-nucleotide complementary sequence theoretically capable of engaging in a KLI. On either side of each loop is two thymines which will not engage in kissing but are present to provide more flexibility and optimal KLI positioning. Our results suggest that the KLI occurs even at physiological salt levels, and that the KLI does not alter the thermodynamics and stability of the two stem structures. The KLI does not involve all five nucleotides, or at least each base-pair stack is not making full contact. Adding a second strand complementary to the bottom of the kissing complex removes flexibility and causes destabilization of the stems. The KLI of this less flexible complex is maintained but the T_M is reduced, indicating an entopic penalty to its formation.

接吻环相互作用（KLIs）是一个常见的基序，在逆转录病毒二聚化，类病毒复制，mRNA和核糖开关中至关重要。此外，KLIs目前用于多种生物技术应用中，例如适体传感器，RNA支架和稳定用于治疗的疫苗。在这里，我们描述了能够参与KLI的基本分子内DNA的热力学，该分子由两个通过柔性接头连接的发夹组成。每个发夹环具有理论上能够参与KLI的五核苷酸互补序列。在每个环的每一侧有两个胸腺嘧啶，它们不会进行接吻，但是会提供更大的灵活性和最佳的KLI定位。我们的结果表明，即使在生理盐水平下，KLI也会发生，并且KLI不会改变两个阀杆结构的热力学和稳定性。KLI不涉及所有五个核苷酸，或者至少每个碱基对堆栈未完全接触。在接吻复合体的底部增加第二条链，会消除柔韧性并导致茎不稳定。保持了这种不太灵活的复合体的KLI，但是T _M降低，表明它的形成受到了物质上的损失。