\Ca\ concentrations\citep{chauhan97,itkin11}. The mechanism behind
this weaker bonding is unclear\citep{chauhan97,zhang06}, although
aspartic and glutamic acid groups tend to have a strong affinity for
-cations while argenine has a strong affinity for the
+cations while arginine has a strong affinity for the
\Cl\ anion\citep{friedman11}. Of these amino acids, only glutamic
acid occurs in the key hydrogen bond regions responsible for I27
unfolding\citep{lu00b} (\cref{fig:I27:H-bonds}). \NaCl\ has also been