Electrostatic and hydrophobic interactions in SARS coronavirus main proteinase dimer

The crystal structures of the three coronavirus main proteinases, SARS 3CL, HCoV 3CL and TGEV 3CL, are used to study the electrostatic and hydrophobic interactions between two monomers. The continuum model and the finite difference Poisson-Boltzmann (FDPB) method were used to calculate the electrostatic potentials on the interface of the three dimers. hi each dimer, the two monomers exhibit apparent electrostatic complementarity and the electrostatic interaction energies are very similar among the dimers. The solvent accessible surface model was applied for the molecular surface and hydrophobicity. The hydrophobic distributions were similar for the three proteinases. Seventy-four percent area of SARS 3CL proteinase surface is hydrophobic which is the main drive of dimer formation. The similar hydrophobic desolvation free energies indicate that electrostatic interaction energies are very similar among the three coronavirus main proteinase dimers.