TABLE 2.

Efficiency of PB1 peptides carrying single alanine or aspartic acid substitutions to compete with PA binding^a

Peptide	Amino acid sequence	Mean IC50 (nM) ± SD
PB11-15	MDVNPTLLFLKVPAQ	41.3 ± 11.1
PB11-15M1A	ADVNPTLLFLKVPAQ	596.7 ± 107.6
PB11-15D2A	MAVNPTLLFLKVPAQ	225.0 ± 63.4
PB11-15V3A	MDANPTLLFLKVPAQ	93.4 ± 31.8
PB11-15N4A	MDVAPTLLFLKVPAQ	>3,000*
PB11-15P5A	MDVNATLLFLKVPAQ	>3,000*
PB11-15T6A	MDVNPALLFLKVPAQ	1,835.7 ± 768.5
PB11-15L7A	MDVNPTALFLKVPAQ	>3,000*
PB11-15L8A	MDVNPTLAFLKVPAQ	>3,000*
PB11-15F9A	MDVNPTLLALKVPAQ	>3,000*
PB11-15L10A	MDVNPTLLFAKVPAQ	>3,000*
PB11-15K11A	MDVNPTLLFLAVPAQ	713.1 ± 140.9
PB11-15V12A	MDVNPTLLFLKAPAQ	427.9 ± 59.3
PB11-15P13A	MDVNPTLLFLKVAAQ	156.5 ± 51.1
PB11-15M1D	DDVNPTLLFLKVPAQ	703.5 ± 279.6
PB11-15V3D	MDDNPTLLFLKVPAQ	>3,000*
PB11-15N4D	MDVDPTLLFLKVPAQ	>3,000*
PB11-15P5D	MDVNDTLLFLKVPAQ	>3,000*
PB11-15T6D	MDVNPDLLFLKVPAQ	>3,000*
PB11-15L7D	MDVNPTDLFLKVPAQ	>3,000*
PB11-15L8D	MDVNPTLDFLKVPAQ	>3,000*
PB11-15F9D	MDVNPTLLDLKVPAQ	>3,000*
PB11-15L10D	MDVNPTLLFDKVPAQ	>3,000*
PB11-15K11D	MDVNPTLLFLDVPAQ	>3,000*
PB11-15V12D	MDVNPTLLFLKDPAQ	1,392.5 ± 330.7
PB11-15P13D	MDVNPTLLFLKVDAQ	414.6 ± 145.0

^aDetermination of the IC₅₀s of PB1_1-15 peptides harboring the indicated amino acid substitutions by competitive ELISA using increasing concentrations of competitive peptides and cell extract containing HA-tagged PA of A/WSN/33. Asterisks indicate the highest concentrations of competitive peptides (3,000 nM) used without detectable inhibitory effect. Amino acid replacements compared to the wt are indicated in boldface.