TABLE 2.

Interactions involving HN residues 216 to 228^a

Residue	Side chain hydrogen bondsb	Side chain van der Waals contacts
F220	S228cbackbone amide N	R212, T213, T214,dI227
S222	S226 backbone C = O	V210, R212, F220, S226
	L224 backbone C = Oe
L224	—	P126, L208, V210, R212, R225
S226	Y205 side chain	L160, S222, T223, T223
	F221 backbone C = Oe

^aBased on the crystallographic structure of the pH 6.5 form of the HN from the L-Kansas isolate. Interactions were predicted by the UCSF Midas Plus Program.

^bAll hydrogen bond lengths were less than 3.0 Å. Intermonomeric interactions are shown in bold-faced.

^cHN residue 228 is an asparagine in HN of the AV isolate.

^dHN residue 214 is a serine in HN of the AV isolate.

^eHydrogen bond mediated via an H₂O bridge.