PEPTIDE BINDING
Terminal Hydrogen Bonds

( reset HLA-A2)
whole peptide view
A number of contacts at the ends of the antigen binding cleft are hydrogen bonds between the peptide main chain and HLA sidechains (cpk, with the bonding atoms enlarged).

These residues are highly conserved among MHC I's and are thought to confer a "universal peptide binding capability."

N-terminal closeup
Peptide main chain atoms from AA 1-3 each participate in at least one hydrogen bond with HLA atoms.
( distances on/off)
C-terminal closeup
Amino acid 9 (Val) of the peptide can form five hydrogen bonds, all main chain peptide atoms to HLA side chains. The C-terminal oxygen alone accounts for three of the five.
( distances on/off)

Amino acid 8 (Gly) main chain O is close enough to the N of Trp147 to form an H bond, but the N is bonded to water instead (not shown in crystal structure).

There are also hydrophobic contacts between HLA and the peptide; you can view a summary by following the link.
Look next at the central a1a2-peptide contacts...