P I S A
Protein Interfaces, Surfaces and Assemblies
Contents • Result Pages • List of Interfaces

List of Interfaces gives the summary of all interfaces, identified in input data. This includes interfaces, found in the asymmetric unit (represented by input file and expanded, if necessary, by applying NCS operations), but also interfaces between ASUs and unit cells, for which the necessary symmetry expansion of ASU is performed. Only unique interfaces are listed in the page. The following data is displayed for each interface:

Monomer 1 Monomer ID of 1st interfacing monomeric unit. 1st monomer is always in its original position, as given in the input file.
Monomer 2 Monomer ID of 2nd interfacing monomeric unit. 2nd monomer is in position identified by the symmetry operation, specified in 4th column.
Spec. Special inteface properties:
    f  :   fixed interface. This means that PISA considers the interfacing monomeric units as permanently attached to each other. See here why PISA may permanently fix ligands on macromolecules.
    x  :   crystalographically propagating interface. If such interface is considered to be permanently engaged, i.e., that interfacing monomers are permanently bound to each other, then, due to symmetry properties of given crystal, these monomers form an infinite substructure.
    o  :   overlap detected. This means that coordinate data is not perfect, and interfacing monomers overlap in interface area.
Sym. op-n Symmetry operation (in fractional space), applied to 2nd monomer.
Sym. ID Symmetry ID, corresponding to symmetry operation in the previous column. The ID has form N_KLM, where N is serial number of the symmetry operation in the corresponding space symmetry group (as used by the PDB); KLM give fractional coordinates of the unit cell relative to the original cell, placed at 555.
Area Interface area.
Delta G Solvation energy gain upon interface formation, kcal/mol.
P-value Hydrophobic P-value of the interface. The lower P-value, the more specific, or statistically surprising, the interface.
Nhb Number of hydrogen bonds formed between the interfacing monomers.
Nsb Number of salt bridges formed between the interfacing monomers.
Nds Number of disulphide bonds formed between the interfacing monomers.

 
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