Hi >From David, "If you select a group consisting of a single residue in a protein the SAS will be computed as if the rest of the protein is not there. Very useful when you want to compute protein-protein interface areas."
=> therefore, if i select a group consisting of a single residue, which is in the core of a protein, it is impossible that water penetrates into the core of the protein so SAS is supposed to be zero. => However, after calculation with g_sas, the SAS_calculation of the single residue residing in the core of the protein is NOT ZERO. => My understanding is that g_sas returns the surface area of the single residue and it does not matter where the single residue locates. right? => The single residue can locate in the core of the protein or on the surface of the protein. The g_sas calculation for the single residue will not make a huge difference unless the single residue deforms/ twists ..... on the surface or in the core of the protein,right ? => How to compute protein-protein interface area? => In the protein + ligands + water system, I want to compute protein-ligand interface, protein-water interface, and ligand-water interface separately. => How? => in the protein + water system, g_sas computes the total SAS fluctuating between 88 and 144 (angstrom_squares) => does it make sense ? => I don't think that protein will swell 50 % plus in the pure water. => But why ?? => How to calculate the surface area of a micelle ? Thank you Lin >> Hi >> The command >> g_sas => Select a group for calculation of surface and a group for output >> >> >> What is the difference between "a group for calculation of surface" >> and "a group for output"? > > Please consult the documentation. From g_sas -h: > > "The program will ask for a group for the surface calculation and a > group for the output. The calculation group should always consists of > all the non-solvent atoms in the system. The output group can be the > whole or part of the calculation group." > Actually this documentation is not correct. The calculation group are those atoms taken into account in the computation, whether or not they are solvent accessible. If you select a group consisting of a single residue in a protein the SAS will be computed as if the rest of the protein is not there. Very useful when you want to compute protein-protein interface areas. > -Justin > >> Thank you >> Lin >> > -- David.
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