TABLE 1.

Interactions in the membrane/water interface

	DMPC	DMPC-Chol	DMPC-Echol
Sterol-Water H-bonds	−	0.8 ± 0.1/Chol	0.7 ± 0.1/Echol
Sterol-PC H-bonds	−	0.28 ± 0.01/Chol	0.40 ± 0.01/Echol
OP		0.20 ± 0.01/Chol	0.33 ± 0.01/Echol
OC		0.08 ± 0.01/Chol	0.07 ± 0.01/Echol
Sterol-PC water bridges	−	0.56 ± 0.01/Chol	0.44 ± 0.01/Echol
OP		0.31 ± 0.01/Chol	0.25 ± 0.01/Echol
OC		0.25 ± 0.01/Chol	0.19 ± 0.01/Echol
Sterol-PC charge pairs	−	0.2 ± 0.1/Chol	0.2 ± 0.2/Echol
PC-PC water bridge	0.57 ± 0.01/PC	0.53 ± 0.01/PC	0.50 ± 0.01/PC
PC-PC charge pairs	2.08 ± 0.04/PC	1.81 ± 0.03/PC	1.46 ± 0.04/PC
OP	1.25 ± 0.04	1.09 ± 0.03	0.91 ± 0.04
OC	0.83 ± 0.03	0.72 ± 0.03	0.55 ± 0.04
PC-Water H-bonds	10.6 ± 0.1/PC	11.5 ± 0.1/PC	11.7 ± 0.1/PC
OP, OC	4.5 ± 0.1	4.8 ± 0.1	5.0 ± 0.1
Choline†	6.1 ± 0.1	6.7 ± 0.1	6.7 ± 0.1

Sterol-water, Sterol-DMPC, and DMPC-DMPC H-bonds, water bridges, and charge pairs in DMPC,^* DMPC-Chol, and DMPC-Echol bilayers. Errors are given in standard errors.

^*From Pasenkiewicz-Gierula et al. (1999) (from 5-ns trajectory).

^†Water in the clathrate.