Table I.

Erbin-Peptide Experimental and Computational Binding Affinities

Peptide	Affinity, IC50 (μM)	Relative affinity	RTln (IC50)	WaterMap -TΔS (kcal/mol)	WaterMap ΔH (kcal/mol)	WaterMap ΔG (kcal/mol)	MW	MM–GB/SA ΔG (kcal/mol)
WETWV	0.02 ± 0.002	1	−8.6	−30.4	−6.8	−37.2	718	−23.9
FETWV	0.16 ± 0.01	8.0	−7.5	−28.1	−6.6	−34.7	678	−22.7
YETWV	0.16 ± 0.01	8.0	−7.5	−28.1	−6.6	−34.7	694	−29.4
WDTWV	0.41 ± 0.06	21	−6.9	−28.9	−7.5	−36.4	704	−21.3
WESWV	0.16 ± 0.01	8.0	−7.5	−30.0	−6.3	−36.3	704	−26.2
WEVWV	0.26 ± 0.01	13	−7.2	−30.5	−6.9	−37.4	716	−23.2
WETFV	3.3 ± 0.2	170	−5.8	−27.1	−4.2	−31.3	679	−23.5
WETPV	66 ± 4	3300	−4.1	−24.5	−3.3	−27.8	630	−14.6
WETWL	1.8 ± 0.1	90	−6.1	−28.8	−3.9	−32.7	732	−29.0
WETWI	1.7 ± 0.1	85	−6.2	−30.4	−6.8	−37.2	732	−29.4
AETWV	1.0 ± 0.1	50	−6.4	−27.5	−6.6	−34.1	603	−22.0
WATWV	2.8 ± 0.7	140	−5.9	−28.1	−7.7	−35.8	661	−19.8
WEAWV	2.0 ± 0.1	100	−6.1	−29.8	−6.1	−35.9	688	−23.3
WETAV	30 ± 7	1500	−4.5	−24.5	−3.3	−27.8	603	−15.4
WETWA	74 ± 4	3700	−4.0	−28.0	−2.6	−30.6	690	−21.3

Experimental affinities were determined as IC50 using a glutathione S-transferase-based chemiluminescence assay.¹⁶ WaterMap affinities were calculated from the overlap of the peptides with the water-sites shown in Figure 1, according to the protocol described in Abel et al.²⁶ MM–GB/SA energies were calculated using Prime,^32,33,35 employing a brief minimization of the protein/peptide structure; peptide strain energies were not included in the total energy. MW, molecular weight.