Dear Francisco --
On 15 Oct 2008, at 17:05, Francisco J. Enguita wrote:
how
can you define a salt-bridge within a protein structure ?
According to Wikipedia:
a salt bridge in proteins is "a relatively weak ionic bond between
positively and negatively charged side-chains of proteins."
Now, at far as I understand (based on "Structure and Mechanism in
Protein Science - Alan Fersht), you have a salt bridge when two
groups are making an hydrogen bond that is favored by electrostatic
interaction, electrostatic energies being weak in water. To quote the
author of the book, let say you have the following equilibrium:
E-NH3+ ------- OH2 + OH2 ------- -O2C-S <==> E-NH3+
------- -O2C-S + H2O ------- H2O
The right-hand side equation would be more "favorable", as the
electrostatic interaction will be more stable than in the left-hand
side where both ions would be in contact with water molecules.
HTH
Kind regards.
-- Leo --
------------------------------------------------------------
Chavas Leonard, Ph.D. @ home
Research Associate
Marie Curie Actions Fellow
------------------------------------------------------------
Faculty of Life Sciences
The University of Manchester
The Michael Smith Building
Oxford Road
Manchester Lancashire
M13 9PT
------------------------------------------------------------
Tel: +44(0)161-275-1586
e-mail: [EMAIL PROTECTED]
http://personalpages.manchester.ac.uk/staff/leonard.chavas/
