Salting-out constants for triglycine were calculated
for a series of Hofmeister salts using molecular dynamics
simulations. Three variants of the peptide were considered with
both termini capped, just the N-terminus capped, and without
capping. The simulations were supported by NMR and FTIR
measurements. The data provide strong evidence that previous
experimental values of salting-out constants assigned to the fully
capped peptide (as previously assumed) should have been assigned
to the half-capped peptide instead. Therefore, these values cannot
be used to directly establish Hofmeister ordering of ions at the
peptide backbone because they are strongly influenced by
interactions of the ions with the negatively charged C terminus.