Table 2.

Solvent interactions with the protein backbone

Interaction site*			Microstate†
N, i	O1, j	O2, k	E, kcal/mol	Ω
+	+	+	−1	Ω+++
+	+	o	0	Ω++o
+	+	−	1	Ω++−
+	o	+	0	Ω+o+
+	o	o	1	Ω+oo
+	o	−	2	Ω+o−
+	−	+	1	Ω+−+
+	−	o	2	Ω+−o
+	−	−	3	Ω+−−
o	+	+	−2	Ωo++
o	+	o	−1	Ωo+o
o	+	−	0	Ωo+−
o	o	+	−1	Ωoo+
o	o	o	0	Ωooo
o	o	−	1	Ωoo−
o	−	+	0	Ωo−+
o	−	o	1	Ωo−o
o	−	−	2	Ωo−−
−	+	+	−3	Ω−++
−	+	o	−2	Ω−+o
−	+	−	−1	Ω−+−
−	o	+	−2	Ω−o+
−	o	o	−1	Ω−oo
−	o	−	0	Ω−o−
−	−	+	−1	Ω−−+
−	−	o	0	Ω−−o
−	−	−	1	Ω−−−

The 27 microstates and their associated energies and degeneracies.

*The single amide nitrogen and two carbonyl oxygen backbone interaction sites are indicated by N, O₁, and O₂, respectively. Solvent interactions with these sites are given by the charge of the interacting solvent surface: positive (+), negative (−), and neutral (o), and i, j, and k indices are varied over the range of values for these interactions.

^†E is the energy of a given microstate, and Ω is its degeneracy.