pI Calculation

[cheethj at ROCKVAX.ROCKEFELLER.EDU]

Does anyone know of a program that will allow the
calculation of isoelectric points and charges at
various pH values for peptides and proteins with
modified residues and blocked amino and/or
carboxyl termini?  Any help with this would be
greatly appreciated.
Jim Cheetham
Laboratory of Molecular and Cellular Neuroscience
The Rockefeller University
CHEETHJ at Rockvax.Rockefeller.EDU