Table 3. Calculated K_ds and derived ΔG° (Gibbs free energy of binding) for the interactions between eIF4E and the derivative peptides used to study the relationship of amino acids at positions 8 and 12 in relation to the presence of the V residue present at position 10.

Peptide	Sequence	Kd from SPR (nM)		(ΔG°, cal mol−1)
		Keq	Kkin	Keq derived	Kkin derived
PHAGESOL	1KKRYSRDQLVAL12	76.7±3.4	77.1±9.0	−9700±20	−9700±70
eIF4G1-OPT	1KKRYSREFLLAF12	52.2±1.4	59.4±2.9	−9920±20	−9850±30
PHAGESOL-Q8F	1KKRYSRDFLVAL12	195.6±6.3	183.8±15.4	−9140±20	−9180±50
PHAGESOL-L12F	1KKRYSRDQLVAF12	111.5±2.7	120.0±5.3	−9470±10	−9430±30
PHAGESOL-Q8F/L12F	1KKRYSRDFLVAF12	348.4±20.9	373.5±33.1	−8800±40	−8760±50
VL-PHAGESOL-Q8F	1KKRYSRDFLLAL12	49.6±4.3	47.15±1.5	−9950±50	−9980±20
VL-PHAGESOL-Q8F/L12F	1KKRYSRDFLLAF12	69.94±6.4	62.0±3.5	−9750±60	−9820±30
VL-PHAGESOL	1KKRYSRDQLLAL12	37.2±1.6	34.7±1.2	−10,120±30	−10,170±20
VL-PHAGESOL-L12F	1KKRYSRDQLLAF12	43.21±0.34	40.7±3.8	−10,040±10	−10,070±60
eIF4G1-QL	1KKRYDREQLLGL12	1093.0±49.9	1087.7±106.1	−8120±30	−8130±60
PHAGESOL-D7E	1KKRYSREQLVAL12	51.6±1.8	52.9±2.1	−9930±10	−9920±20

The table shows the peptide sequences used to study the relationship of amino acids at positions 8 and 12 in relation to the presence of the V residue present at position 10. K_ds were determined using SPR with eIF4E immobilized via amine coupling on the chip surface. K_ds were derived from the equilibrium responses (K_eq) and from the association and dissociation phases (K_kin) of the SPR data. The Gibbs free energy of binding (ΔG°) was calculated with the equation ΔG = -RT ln K_a using both dissociation constant values determined.