1 BOA 2-bromo-6-hydroxy-purine 1.000 2 HPA Hypoxanthine 0.909 3 2ON 2-sulfanyl-1,9-dihydro-6h-purin-6-one 0.833 4 BCP 2-bromo-6-chloro-purine 0.833 5 GUN Guanine 0.833 6 XAN Xanthine 0.833 7 5JL 2,8-dithioxo-1,2,3,7,8,9-hexahydro-6h-purin-6-one 0.769 8 5JQ 2-thioxo-2,3,7,9-tetrahydro-1h-purine-6,8-dione 0.769 9 8HX 8-hydroxy-3,9-dihydro-1h-purine-2,6-dione 0.769 10 8IG 8-iodo-guanine 0.769 11 8TX 8-thioxo-3,7,8,9-tetrahydro-1h-purine-2,6-dione 0.769 12 9MG 9-methylguanine 0.769 13 ANG 8-aminoguanine 0.769 14 B55 2-amino-8-sulfanyl-1,9-dihydro-6h-purin-6-one 0.769 15 BRG 8-bromoguanine 0.769 16 MY6 2-amino-7-methyl-1,7-dihydro-6h-purin-6-one 0.769 17 OXG 8-oxoguanine 0.769 18 URC Uric acid 0.769 19 2BP 9h-purin-2-amine 0.750 20 6MP 6-methylpurine 0.750 21 7HX 7h-pyrrolo[2,3-D]pyrimidin-4-ol 0.750 22 9HX 9-deazahypoxanthine 0.750 23 ADE Adenine 0.750 24 BP1 6-bromo-7h-purine 0.750 25 ES4 6-chloro-9h-purine 0.750 26 PM6 9h-purine-6-thiol 0.750 27 28Y 3h-imidazo[2,1-B]purin-4(5h)-one 0.714 28 37T Theobromine 0.714 29 MUA 9-methyl uric acid 0.714 30 NDM 7,9-dimethylguanine 0.714 31 TEP Theophylline 0.714 32 UAN 9-methyl-2-(methylamino)-1h-purin-6-one 0.714