logo.gif (3296 bytes)Introduction to Protein Structure

Overall Charge on a Peptide -- Example 1


Valinylisoleucylleucylmethionine
(Val-Ile-Leu-Met; VILM)

wpe20.jpg (9000 bytes)

Note: the ionizable groups are "boxed"

The only ionizable groups in this peptides are the amino group (pka ~ 9) and the carboxyl group (pKa ~ 3) at each end of the molecule.

Thus, the net charge on this peptide at three different  pH's ( 2, 7 and 11) is as follows:

Charge on Functional Group
pH N-terminus C-terminus Net Charge
2.0 1+ 0 1+
7.0 1+ 1-
11.0 1- 1-

Copyright 1998, 1999, 2007 by Frank R. Gorga;   Page maintained by F.R. Gorga;   Last updated: 12-Mar-2007