Table 3. Intermolecular interactions of the C9-substituents (terminal atom) in the E/Z isomers with the hydrophobic residues in the active site of DHFR.

	Distance (Å) between inhibitor C9 and
	Ile60 CD1	Ile67 CD1	Val115 CG2	Thr56 CD1
mDHFR E1	4.7	5.0	4.4	3.9
mDHFR Z1	3.9	4.3	3.7	3.6
hDHFR Z1	3.9	4.7	4.4	3.6
hDHFR Z3	3.6	4.5	3.4	3.5
hDHFR E2	4.2	4.3	4.0	4.1
hDHFR E4	3.5	4.5	4.0	3.5
hDHFR E5	4.2	3.9	3.5	3.8
hDHFR E6	3.9	4.5	3.5	3.4
hDHFR E7	4.5	4.4	3.5	3.9