1. O F H N3 O H N1 dRib P The synthesis of thymine by thymidilate synthetase O H N N H2N H H CH2 + N3 N5, N10-Methylene tetrahydrofolate H N H H CH2 O N N1 O 2HC N dRib P dUMP R thymidilate synthetase FdUMP Methyltransferase O H N N tetrahydrofolate CH3 H2N H CH2 N3 N H CH2 O H N N1 O NH dRib P DHFR R dTMP dihydrofolate FdUMP DHFR Antifolates Aminopterin Methotrexate Trimethoprim Folate diet Sulfonamides de novo synthesis inbacteria (pp 762-764 V&V)