Table 2. Free Energies from One-step Perturbation for Both Reference States in the G171 Site^a.

P1′	mut at 171	RDR p_contr	RDR ΔΔGR>N	R2R p_contr	R2R ΔΔGR>N
Ile	Ala	64.84	–10.6	4.78	–6.4
	Arg	0.31	5.2	2.11	–2.0
	Asn	28.96	4.0	11.41	1.5
	Asp	26.68	–12.9	12.18	–5.1
	Cys	1.13	–4.3	1.89	2.3
	Gly	8.45	3.8	4.24	0.7
	Gln	4.51	–13.0	11.45	–7.8
	Glu	5.20	–10.4	13.13	–8.6
	HisA	2.29	5.4	10.22	2.5
	HisB	2.27	3.0	10.28	2.7
	Ile	3.36	1.9	3.76	1.6
	Leu	10.75	4.0	6.06	–1.2
	Lys	1.29	–3.4	8.88	–2.2
	Met	3.46	3.2	11.04	0.8
	Phe	0.42	7.9	3.93	3.7
	Ser	53.00	–0.05	8.85	2.3
	Thr	31.76	1.3	6.20	1.8
	Trp	0.22	0.3	0.68	1.3
	Tyr	0.32	10.2	2.44	17.2
	Val	10.02	–4.9	5.58	1.5
Pro	Ala	67.34	13.8	41.12	28.6
	Arg	0.33	–3.3	2.79	4.5
	Asn	38.82	1.0	34.36	19.6
	Asp	44.67	2.4	32.47	6.2
	Cys	48.66	4.7	7.22	23.5
	Gly	2.34	2.4	1.77	2.9
	Gln	26.00	1.0	8.23	12.6
	Glu	25.12	–2.9	12.90	2.9
	HisA	6.08	–1.4	17.49	12.7
	HisB	7.10	1.2	21.91	13.6
	Ile	11.04	–7.6	3.36	11.6
	Leu	25.86	–5.4	8.82	10.3
	Lys	2.55	–6.9	12.12	10.8
	Met	8.28	2.0	19.70	12.4
	Phe	1.18	–17.4	8.95	8.9
	Ser	58.28	7.7	36.09	25.4
	Thr	39.23	1.2	13.80	19.4
	Trp	0.26	–26.5	4.64	6.0
	Tyr	0.46	–14.8	4.86	4.5
	Val	34.84	–4.7	6.79	17.0

^aFree energies are reported for two P1′ amino acids, Ile and Pro. Next to the ΔΔG values (reported in kJ/mol), the percentage of contributing frames are reported as an average over both bound and apo states.HisA: N^δ1–H tautomer; HisB: N^ϵ2–H tautomer.