Program to calculate isoelectric points?

Keith Robison robison at
Tue Jul 11 07:01:41 EST 1995

Samuel C. Blackman (scb1 at wrote:
: Does anyone know of a program (Mac, DOS, Unix) that will calculate the
: isoelectric point of a given peptide?  Thanks!

Most commercial packages include such a function/program.  
As another poster suggested, you might ask around.

An alternative is Netscape or Mosaic -- point it at

where the good folks at ExPASy have a nice little service which
will do the calculation.

Note that all of these programs calculate the pI of the
_unfolded_, _unmodified_ protein.  Useful for predicting
the position on an IEF or 2-D gel, but perhaps not for
other purposes.

Keith Robison
Harvard University
Department of Cellular and Developmental Biology
Department of Genetics / HHMI

robison at 

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