It would be nice that Chimera also compute and save the SAS (like a grid), since there're a few softwares to do this task spacifically. I hope this will avaible in the future... Anywere, thanks a lot for your helps -- Lic. Yasser Almeida Hernández Center of Molecular Inmunology (CIM) Nanobiology Group P.O.Box 16040, Havana, Cuba Phone: (537) 271-7933, ext. 221 ---------------------------------------------------------------- Correo FENHI