Specificity of Watson-Crick Base Pairing on a Solid Surface Studied at the Atomic Scale

摘要

The fascinating double-helix structure of DNA, discovered by Watson and Crick fifty years ago, provides a simple model for DNA replication based on the principle of complementary base-pairing sets of guanine (G)/cytosine (C) and adenine (A)/thymine (T). This base-pairing scheme is thought to play a crucial role in the fidelity with which DNA is replicated, since it would impose an enthalpy penalty to form double-stranded DNA from error-containing strands. In the absence of polymerases in the prebiotic soup, base pairing triggered by hydrogen bonds is thought to be the crucial factor for the recognition of nucleobases, and base pairing probably also played an important role in the polymerization of the first oligonucleotide. It has been shown that short RNA strands can act as templates that catalyze the polymerization of complementary RNA strands from activated nucleotides insolution. However, the reaction proceeds slowly, and the replication process is relatively unfaithful. Better estimations of binding energies associated with all possible interactions involved in nucleobase recognition would help to clarify the issue, but hitherto it has been difficult to design experiments in which the different contributions of hydrogen bonding, solvation energy, and hydrophobic and van der Waals interactions can be determined separately. The development of scanning probe microscopy methods has given us an invaluable tool to explore intermolecular interactions in the presence of a surface.