I would guess that an extended system of conjugated pi electron can make
some nice interactions with a polar molecule like water. Therefore, the
aromatic side chains should be less hydrophobic than the
aliphatic ones, and also the deprotonated aspartate with it's pi
electrons delocalized over both oxygens should be less hydrophobic
than the protonated aspartic acid.
So, an alipathic side chain like Isoleucine should be the most
hydrophobic. For the most hydrophilic side chain I would take
into account aspartate (pK 4.4), glutamate (pK 4.4) and arginine (pK 12.0).
For arginine the pK is most different from 7 and I would conclude,
that arginine is the most polar and the most hydrophilic side chain.
--- Peter Slickers firstname.lastname@example.org Institut fuer Molekulare Biotechnologie Beutenbergstrasse 11, Jena Tel.: +49-3641-65-6202 Postfach 10 08 13, D-07708 Jena, Germany Fax: +49-3641-65-6210