Table 1.

Hydrogen exchange rates measured for arginine side‐chains in T4 L.

Residue	k ex [s−1][a]	k ex [s−1][b]	PF
R8	2.6±0.2	ND [d]	6.0±0.5
R14	4.6±0.2	ND [d]	3.4±0.2
R52	ND [c]	8.9±1.8	348±70
R76[e]	4.24±0.16	ND [d]	3.6±0.2
R80[e]	4.24±0.16	ND [d]	3.6±0.2
R95	ND [c]	ND [d]	2.2±0.5×105[e]
R96	ND [c]	22±5	141±32
R119[f]	4.24±0.16	ND [d]	3.6±0.2
R125[f]	4.24±0.16	ND [d]	3.6±0.2
R137[f]	4.24±0.16	ND [d]	3.6±0.2
R145	ND [c]	1.4±0.4	2200±600
R148	ND [c]	2.6±0.4	1200±200
R154	1.51±0.10	ND [d]	10.2±0.8
Free Arg	15.5±0.5	3100±100[g]

[a] Extracted rate constants, determined at pH 5.5, 298 K; [b] Exchange rate constants, determined at pH 7.4; 308 K; [c] Exchange too slow to be determined; [d] Exchange too fast to be determined; [e] Determined from ¹H‐¹⁵N HSQC experiments as described in the Supporting Information; [f] Overlap of these residues prevented a residue‐specific measurement; [g] The rate for free arginine at pH 7.4 and 308 K is extrapolated from the linear dependence in Figure 5.