(1) CH3 H NH2 HN H N CH3 0 -H N H N R dR dR 5.6-dihydrouridine (D or hU) N6-Methyl-dA 5-Methyl-dC (2) Ade HOCH2 H H H H OH OCH3 2-O-甲基腺苷(Am)N N NN N H C H 3d R N 6 - M e t h y l - d A ( 1 ) H N N H O 5 , 6 - dih y d r o u ridin e O R HHH ( D o r h U ) ( 2 ) O C H 2 H HO H HO C H 3H H O2'- O - 甲 基 腺 苷 A d e ( Am ) N N C H 3 N H 2 5 - M e t h yld C O d R