Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Chemical structure and atomic numbering of the canonical GC base pair. Both N9 in G and N1 in C are the connections to the lateral backbone in DNA. In an isolated GC base pair, these positions are occupied by two hydrogen atoms. Arrows show the possible displacements of the protons H1, H4, and H4′ during the tautomeric reactions.
