What positions in the ring of a purine nucleotide in DNA have the potential to form hydrogen bonds but are not involed in watson-crick base pairing?

N-1

Explanation:

All nitrogen positions in purine rings (N-1, N-3, N-7 and N-9) have the potential to form hydrogen bonds. Among them, only N-1 is involved in Watson-Crick base pairing hydrogen bond with a pyridimine. N-3 and N-7 are available to form further hydrogen bonds and N-9 is involved in a N-glycosyl linkage with a desoxyribose.