P-degrees of salt bridges in the concatenated equilibrium MD trajectories of the psychrophilic VPR, mesophilic PRK, and thermophilic AQN at temperatures of 283, 300, and 343 K.

Salt bridgea	VPRb (%)			PRKb (%)			AQNb (%)
	283 K	300 K	343 K	283 K	300 K	343 K	283 K	300 K	343 K
	100	100	100	100	100	100	100	100	100
	—	—	—	100	100	100	—	—	—
Arg16-Asp278 (c)	25	34	45	—	—	—	—	—	—
Asp17-Arg260 (c)	—	—	—	—	—	—	100	99	99
Asp29-Lys86	19	0	27	—	—	—	—	—	—
Arg31-Glu239 (c)	—	—	—	—	—	—	78	57	66
Glu43-Arg64	—	—	—	68	40	73	—	—	—
	—	—	—	—	—	—	86	65	28
	—	—	—	—	—	—	0	8	20
Glu48-Arg80 (c)	—	—	—	98	95	74	—	—	—
	—	—	—	93	90	93	—	—	—
	—	—	—	34	47	59	—	—	—
	100	100	100	—	—	—	84	100	100
	99	98	99	—	—	—	—	—	—
	—	—	—	0	40	6	—	—	—
	—	—	—	—	—	—	7	31	37
	—	—	—	96	68	90	—	—	—
Asp112-Arg116	—	—	—	—	—	—	79	61	81
Asp112-Arg147 (c)	—	—	—	38	50	62	—	—	—
Asp117-Arg121 (c)	—	—	—	100	100	99	—	—	—
Asp142-Arg173 (c)	95	99	100	—	—	—	100	100	94
Lys146-Glu176	—	—	—	—	—	—	65	34	62
Asp165-Arg167	—	—	—	36	41	85	—	—	—
Asp184-Arg188 (c)	—	—	—	93	87	74	—	—	—
Arg185-Asp207	—	—	—	37	21	13	—	—	—
	34	85	90	—	—	—	—	—	—
Glu240-Arg255 (c)	100	99	98	—	—	—	—	—	—
Arg250-Asp254	—	—	—	19	47	40	—	—	—
Glu258-Lys271	62	75	79	—	—	—	—	—	—
	22	55	78	—	—	—	—	—	—

^aSalt bridges identified in the crystal structures are followed by ‘c’ in parentheses; salt bridges common to the three proteases (absolutely conserved) are in bold; salt bridges shared between VPR and AQN (conserved) are bolded and italicized; salt bridges participating in the salt-bridge network are underlined.

^b P-degree is the percentage of the frames in which a given salt bridge exists. If a salt bridge does not exist at any temperature, it is indicated as ‘—’; if the P-degree of a salt bridge at any of the three temperatures is greater than 20%, its P-degrees at all three temperatures are also shown.