TABLE 3.

Parameters of protein-protein interaction for E. coli FPPs, S. solfataricus HexPPs, and T. maritima OPPs^a

Interface parameter	FPPs	HexPPs	OPPs	Homodimera
ΔASAb (Å2)	1,800	1,820	1,712	1,685
% ΔASA	14.12	12.68	11.35
% Polar atoms in interface	28.25	27.05	31.76
% Nonpolar atoms in interface	71.70	72.90	68.20
Hydrogen bonds	9	5	6
Salt bridges	2	0	4
Gap volumec (Å2)	3,814	5,809	6,829
Gap volume index	1.09	1.63	2.01	2.2

^aA mean value from the data set of 32 nonhomologous homodimers (11).

^bThe protein-protein interface has been defined based on the change in their solvent accessible surface (ΔASA).

^cThe gap volume between the two components of the complexes was calculated using SURFNET.

^dInteractions at the dimer interface were analyzed using the Protein-Protein Interaction Server (11).