Table 1.

Occurrence of hydrogen bonds (%) to DNA and water, and hydration shell number of water molecules for netropsin and distamycin free in solution and in complex with DNA

Netropsin				Distamycin
Atoms	Free water	Complex		Atoms	Free water	Complex
		DNA	Water			DNA	Water
N1–H11→	76	1	76	N1–H11→	76	0	81
N1–H12→	82	35	31	N1–H12→	83	45	22
N2–H21→	72	0	81	N2–H21→	76	0	80
N2–H22→	82	46	26	N2–H22→	82	36	30
N3–H3→	59	41	0	N3–H3→	60	44	0
O1←	76	0	90	O1←	72	0	91
N4←	14	0	14	N4←	13	0	17
N5–H5→	58	33	0	N5–H5→	58	43	0
N5←	4	0	2	N5←	4	0	0
O2←	84	0	91	O2←	85	0	90
N6←	14	0	11	N6←	13	0	20
N7–H7→	77	61	0	N7–H7→	66	76	0
N7←	3	0	0	N7←	5	0	1
O3←	66	0	69	O3←	84	0	89
N8–H8→	79	13	56	N8←	14	0	16
N8←	0	0	0	N9–H9→	71	41	0
N9–H91→	67	0	68	N9←	6	1	4
N9–H92→	57	9	41	O4←	86	0	76
N10–H101→	67	1	73
N10–H102→	59	47	5
Total	11.9	3.1	8.1	Total	11.2	3.2	7.5
$N_{\text{w}}^{\text{shell}}$	10.2		5.5	$N_{\text{w}}^{\text{shell}}$	7.3		2.7

For every hydrogen bonding atom in the ligands, the occurrence of hydrogen bonds (>1%) to (→) and from (←) water and to and from DNA is given. A hydrogen bond is defined by a donor–acceptor distance <0.25 nm and a donor–hydrogen–acceptor angle >135°. The atom labelling is indicated in Figure 6. The average number of hydrogen bonds between ligands on the one hand and DNA and water on the other is given in the row labelled ‘Total’. The average number of water molecules within a shell of radius 0.245 nm around the atoms of the ligand is given in the row labelled $N_{\text{w}}^{\text{shell}}$.