AVS 51st International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI2-WeM

Paper BI2-WeM6
Molecular Recognition in 2D Binary Mixtures of DNA-Base Molecules Studied by STM

Wednesday, November 17, 2004, 10:00 am, Room 213C

Session: Oligo Nucleotide - Surface Interactions
Presenter: M. Schöck, University of Aarhus, Denmark
Authors: M. Schöck, University of Aarhus, Denmark
R. Otero, University of Aarhus, Denmark
L.M. Molina, University of Aarhus, Denmark
E. Laegsgaard, University of Aarhus, Denmark
I. Stensgaard, University of Aarhus, Denmark
B. Hammer, University of Aarhus, Denmark
F. Besenbacher, University of Aarhus, Denmark
Correspondent: Click to Email
Molecular recognition events between complementary nucleic acid bases are fundamental for many biological processes, like DNA replication, and is currently being exploited for self-assembling DNA-based nanostructures. The DNA replication fidelity in living organisms is maintained by a complex molecular machinery of polymerases, exonucleases, etc. On the other hand, in the case of replicating NA molecules in the prebiotic soup, the basic physico-chemical mechanism to steer the replication process is the hydrogen-bonding between DNA bases. The fidelity of this replication process implies that Watson-Crick pairing must be favored over others, like "wobble" or "deviant" pairing. By means of a combination of STM experiments and DFT calculations, in this contribution we compare the 2D molecular networks formed on Au(111) upon deposition of the binary mixtures G-C (purine-pyrimidine pair of complementary bases) and A-C (purine-pyrimidine pair of non-complementary bases). We show that, after a gentle annealing to 80°C the non-complementary bases segregate into islands of pure A and a network of pure C, whereas the complementary bases G and C form a network that cannot be separated by annealing up to the desorption temperature for C. High-resolution STM images allow us to identify the structures for these enhanced thermal stability as structures that contain G-C bonds possibly with the same structure as the Watson-Crick pairs in DNA molecules. This result shows that the hydrogen-bonding interaction alone can steer the molecular recognition process necessary for high-fidelity DNA replication even in the absence of polymerases, exonucleases, etc.,a result that could be relevant to understand the origin and nature of the first self-replicating molecules in the prebiotic soup.