Table 1. Absolute and normalized frequency of total and salt-bridge forming acidic and basic residues as obtained from 20 halophilic proteins (see Materials and Methods).

Residues/class
Arg	279	5.61	127	2.55	45.45
Lys	144	2.89	57	1.14	39.44
His	129	2.59	39	0.78	30.11
Basic	552	11.09	223	4.47	40.30
Asp	501	10.07	126	2.53	25.12
Glu	482	9.69	145	2.92	30.13
Acidic	983	19.76	271	5.45	27.58
Total	1535	30.85	494	9.92	32.16

: Residues absolute frequency in 20 protein chains in the database. : Percent frequency w.r.t. total residues (4975). : Residues salt-bridge absolute frequency. : Percent salt-bridge frequency w.r.t total residues. : Percent salt-bridge frequency w.r.t. corresponding salt-bridge forming residues. Total residues in 20 unique chains 4975.