H-bonding side-chains

[colby]

Can the side chain of a tryptophan residue accept a H-bond? What about
an arginine residue?

According to http://swift.embl-heidelberg.de/future/aainfo/hbonds.html,
the only site on the web I found that discusses amino acid side chain
H-bonding, these two residues do not seem to accept H-bonds. Is it
because of steric hindrance by the atoms that the N-atoms are bonded to?
If so, why does it not affect the H-bond accepting capability of
histidine?

I appreciate any replies.