Department of Chemistry and Biochemistry, and Center for Single Molecule Biophysics, Biodesign Institute at Arizona State University, 1001 South McAllister Avenue, Tempe, Arizona 85287-5601, USA.
Nano Lett. 2013 Jun 12;13(6):2980-8. doi: 10.1021/nl4016107. Epub 2013 May 30.
In biomolecular programming, the properties of biomolecules such as proteins and nucleic acids are harnessed for computational purposes. The field has gained considerable attention due to the possibility of exploiting the massive parallelism that is inherent in natural systems to solve computational problems. DNA has already been used to build complex molecular circuits, where the basic building blocks are logic gates that produce single outputs from one or more logical inputs. We designed and experimentally realized a three-input majority gate based on DNA strand displacement. One of the key features of a three-input majority gate is that the three inputs have equal priority, and the output will be true if any of the two inputs are true. Our design consists of a central, circular DNA strand with three unique domains between which are identical joint sequences. Before inputs are introduced to the system, each domain and half of each joint is protected by one complementary ssDNA that displays a toehold for subsequent displacement by the corresponding input. With this design the relationship between any two domains is analogous to the relationship between inputs in a majority gate. Displacing two or more of the protection strands will expose at least one complete joint and return a true output; displacing none or only one of the protection strands will not expose a complete joint and will return a false output. Further, we designed and realized a complex five-input logic gate based on the majority gate described here. By controlling two of the five inputs the complex gate can realize every combination of OR and AND gates of the other three inputs.
在生物分子编程中，利用蛋白质和核酸等生物分子的特性来实现计算目的。由于可以利用自然系统固有的大规模并行性来解决计算问题，该领域引起了相当大的关注。已经使用 DNA 来构建复杂的分子电路，其中基本构建块是逻辑门，这些逻辑门从一个或多个逻辑输入中产生单个输出。我们设计并通过实验实现了基于 DNA 链置换的三输入多数门。三输入多数门的一个关键特征是三个输入具有同等优先级，如果两个输入中有一个为真，则输出为真。我们的设计由一个中央的圆形 DNA 链组成，该链具有三个独特的结构域，三个结构域之间有相同的连接序列。在向系统引入输入之前，每个结构域和每个连接的一半都被一条互补的单链 DNA 保护，该单链 DNA 显示出随后由相应输入置换的立足点。通过这种设计，任何两个结构域之间的关系类似于多数门中输入之间的关系。置换两个或更多保护链将暴露至少一个完整的连接，并返回真输出；不置换任何一个或仅置换一个保护链将不会暴露完整的连接，并返回假输出。此外，我们设计并实现了基于这里描述的多数门的复杂五输入逻辑门。通过控制五个输入中的两个，复杂门可以实现其他三个输入的 OR 和 AND 门的所有组合。
