Getting poster data...
Izabella Neshich (UNICAMP, Campinas, Brazil)Several studies have revealed that interface region of monomers has been found to be more hydrophobic than the rest of solvent-exposed surface. Interested on hydropobicity of protein surface in complexes and their isolated subunits, we decided to introduce a parameter, derived from the known scales (such as Kyte-Doollittle), normalizing aminoacid Hydropathy by their effective accessible surface area: the Aminoacid Normalized Hydrophobicity Index (ANHI). A new parameter was calculated: Surface Hydrophobicity Index (SHI), which describes the cumulative surface Hydrophobicity for an isolated chain and in complex with another chain. SHI is calculated as the sum of all normalized ANHI of Hydrophobic (HB) residues, divided by the sum of ANHI of all Hydrophilic (HL) residues for a selected PDB chain. Thus, low SHI values are indicators of the hydrophilic protein surfaces. Applying our method to the PDB containing only protein chains we found that 96.7% of oligomeric proteins in PDB have their SHI value in isolation higher (more hydrophobic) than in complex. This data suggests that protein association (for the data mart we examined) is effectively driven by hydrophobic effect where more