define polar_atoms oxygen, nitrogen
echo polar_atoms is oxygen, nitrogen
define unpolar_atoms carbon, *.P, sulphur
echo unpolar_atoms is carbon, *.P, sulphur


define dnk :I, :J
echo dnk is :I, :J

define polar_dna polar_atoms and dnk and within(3.5, (protein and polar_atoms))
echo polar_dna

define unpolar_dna unpolar_atoms and dnk and within(4.5, (protein and unpolar_atoms))
echo unpolar_dna


define riboza (*.C1*, *.C2*, *.C3*, *.C4*, *.C5*, *.O4*)
echo riboza

define fosfat (*.P, *.O1P, *.O2P, *.O3*, *.O5*)
echo fosfat


define ao (*.N1, *.C6, *.C5, *.C4, *.N3, *.C2, *.O2, *.N4, *.C7, *.O4, *.N9, *.C8, *.N7, *.N6, *.N2, *.O6) and (purine, pyrimidine)
echo ao