TABLE 1.

Parameters characterizing Heisenberg exchange rates for R1 in T4L

Residue	kex(NiEDDA)*	kex(O2)	kex(O2)/kex(NiEDDA)	fsa†	fV‡	ρ
44	0.213	1.89	8.85	0.80	0.42	0.64
65	0.173	1.52	8.76	0.74	0.36	0.52
72	0.140	1.67	11.90	0.55	0.38	0.42
74	0.040	0.70	17.59	0.10	0.07	0.12
81	0.197	1.59	8.10	0.17	0.18	0.59
89	0.290	2.00	6.90	0.57	0.41	0.87
128	0.290	2.00	6.90	0.55	0.49	0.87
129	0.037	0.70	19.19	0.00	0.10	0.11
130	0.173	1.44	8.33	0.12	0.15	0.52
131	0.233	2.07	8.89	0.68	0.44	0.70
132	0.300	1.78	5.93	0.31	0.27	0.90
133	0.003	0.19	55.56	0.01	0.06	0.01
134	0.147	1.52	10.35	0.30	0.22	0.44
135	0.333	2.04	6.11	0.80	0.44	1.00

^*k_ex = Π/C_R, where C_R is the concentration of reagent corresponding to Π.

^†f_sa is the fractional surface area accessibility of the native side chain calculated according to Lee and Richards (31).

^‡f_V is the fractional volume accessibility computed as described in Materials and Methods.