Table 1.

Calculated free energy of binding for target and standard amino acids to their cognate synthetase enzymes (ΔG_binding ≤ −6.0 kcal/mol shown in bold). The target ligand for the pBpa synthetase is ligand 1, and the target ligand for the 8Ala synthetase is ligand 4. The six synthetase enzymes shown in Figure 2 correspond to the six columns of this table.

	pBpa Synthetase	8Ala Synthetase	Synthetase Design for Ligand 4	Synthetase Design for Ligand 5	Synthetase Design for Ligand 7	Synthetase Design for Ligand 2
Target Ligand	−8.9	−9.2	−12.8	−11.2	−12.7	−7.4
Ala	−1.6	−0.9	−1.4	0.1	−2.4	−2.0
Arg	3.8	3.6	2.2	5.6	−2.4	5.5
Asn	−0.2	−3.1	−3.0	−4.6	−5.2	−3.2
Asp	8.1	3.9	2.0	6.8	1.0	2.0
Cys	−0.3	0.8	0.4	−1.5	−3.3	−1.6
Gln	−4.6	−0.9	−3.9	−4.6	−1.5	−3.4
Glu	9.0	−3.5	7.0	7.9	7.0	5.6
Gly	0.6	2.0	1.0	0.4	−0.8	−0.6
His	−2.5	−0.4	−2.0	−4.0	−4.7	−2.5
Ile	−5.2	−2.5	−3.3	−5.7	−3.1	−8.3
Leu	−6.1	−3.5	−6.3	−8.5	−4.5	−8.0
Lys	5.6	1.2	0.7	−0.2	3.7	1.8
Met	−0.3	−1.6	−3.6	−0.7	−1.5	−0.7
Phe	−5.5	−5.0	−5.1	−4.5	−5.5	−5.9
Pro	−4.4	−3.0	−2.6	−4.9	−4.4	−2.9
Ser	0.6	1.8	0.3	0.0	−3.1	0.5
Thr	1.0	1.1	−0.9	0.5	−1.9	−0.9
Trp	0.3	2.2	0.8	−0.3	−0.8	0.0
Tyr	−4.9	−2.7	−4.4	−6.5	−5.3	−5.3
Val	−3.4	−0.5	−2.7	−3.0	−2.5	−3.4