Table 2.

Comparison of key hydrogen-bonding interactions at the α-amino binding site of subunit A in the unliganded and liganded states

Group	Hydrogen-bonding partners and distances
Unliganded state (subunit A)
Glu 47 OE1	Arg 8 NH2 (2.82), water 11 (2.71)
Glu 47 OE2	Arg 8 NH2 (2.93), Arg 8 NH1 (2.88), water 4 (2.40)
Glu 47 O	Leu 50 N (3.01), water 11 (2.64)
Arg 8 NH1	Glu 47 OE2 (2.88), water 36 (2.71)
Arg 8 NH2	Glu 47 OE1 (2.82), Glu 47 OE2 (2.93), Ser 52 O (3.06)
Leu 50 O	Water 11 (2.71)
Ser 52 O	Arg 8 NH2 (3.06)
Water 4	Glu 47 OE2 (2.40), Leu 11 N (2.55), Cys 21 O (3.02)
Water 11	Glu 47 OE1 (2.17), Glu 47 O (2.64), Leu 50 O (2.71)
Water 36	Arg 8 NH1 (2.71)
Vasopressin complex
Cys 1 α-N (VK)	Glu 47 OE1 (2.77), Leu 50 O (2.68), Ser 52 O (2.77), Glu 47 O (2.76)
Glu 47 OE1	Cys 1 α-N (2.77)
Glu 47 OE2	Arg 8 NH1 (2.52), Leu 11 N (3.08)
Glu 47 O	Leu 50 N (3.04), Cys 1 α-N (2.76)
Arg 8 NH1	Glu 47 OE2 (2.52)
Arg 8 NH2	Ser 52 O (2.76)
Leu 50 O	Cys 1 α-N (2.68)
Ser 52 O	Cys 1 α-N (2.77), Arg 8 NH2 (2.76)

Numbers in parentheses are distances in Angstroms. Waters are assumed hydrogen bonded when distances are <3.4 Å.