Table 1. Distances (in Å) between Cα Atoms for Residues Spanning the Ligand Binding Sites in L. casei DHFR and Its Complexes with TMP and NADPH^a.

Res 1	Res 2	apo DHFR	TMP	NADPH	ternary	TMP-apo DHFR	NADPH-apo DHFR	ternary-apo DHFR
R44 Cα	Q101 Cα	10.09	9.22	9.40	9.29	−0.87	−0.69	−0.80
R43 Cα	Q65 Cα	9.86	9.49	8.79	9.56	−0.37	−1.07	−0.30
R43 Cα	H64 Cα	9.32	8.39	7.62	8.60	−0.93	−1.70	−0.72
H77 Cα	Q101 Cα	12.06	12.91	12.74	13.12	0.85	0.68	1.06
H64 Cα	A105 Cα	12.59	10.05	12.73	13.40	−2.55	0.14	0.81
G14 Cα	T45 Cα	11.58	11.87	10.54	9.59	0.29	−1.04	−1.99
A6 Cα	T45 Cα	15.92	13.35	14.02	13.88	−2.57	−1.90	−2.04
I13 Cα	A97 Cα	11.33	11.99	10.47	10.95	0.66	−0.86	−0.38
D26 Cα	A97 Cα	13.57	13.55	11.95	13.03	−0.02	−1.61	−0.54
L4 Cα	L27 Cα	11.82	11.17	11.27	11.18	−0.66	−0.56	−0.64
L27 Cα	F49 Cα	13.42	11.01	12.26	11.21	−2.41	−1.16	−2.21

^aDistances are the average values from all 25 structures in the apo DHFR family.