Table 3.

Energy contributions to the specificity of the substrates due to systems A and B, in kcal mol⁻¹

Residue	System A			System B
	ΔH f(8OG)R	ΔH f(GMP)R	Specificity energya	ΔH f(8OG)R	ΔH f(GMP)R	Specificity energyb
Asp119	−24328.99	−24262.90	−0.32	−19307.03	−19240.04	−0.27
Asp120	−24330.10	−24263.40	+0.29	−19298.65	−19231.54	−0.16
Asn33	−24365.65	−24300.19	−0.96	−19351.29	−19285.08	−1.05
Leu9	−24415.26	−24349.13	−0.28	−19392.44	−19325.05	+0.12
Lys23	−24492.09	−24426.03	−0.34	−19471.20	−19404.28	−0.35
Met81	−24434.66	−24369.51	−1.27	−19408.82	−19342.78	−1.23
Trp117	−24449.51	−24385.23	−2.12	−19436.33	−19371.44	−2.38
Phe27	−24457.49	−24392.04	−0.95	−19434.35	−19366.94	+0.14
Val83	−24425.62	−24359.08	+0.13	−19400.40	−19333.20	−0.06
Phe72	−24449.37	−24385.15	−2.19	−19424.21	−19360.74	−3.79
H2O-2134	−24366.34	−24301.07	−1.14	−19342.02	−19275.74	−0.99
Trp123	−24450.28	−24382.71	+1.16	−19424.93	−19357.47	+0.20
Phe139	−24448.58	−24383.16	−0.99	−19424.55	−19358.75	−1.47

^a Energy = ΔH _f(8OG)_R − ΔH _f(GMP)_R − 66.41.

^b Energy = ΔH _f(8OG)_R − ΔH _f(GMP)_R − 67.26.

A negative specificity implies that the residue binds to the 8-oxo-dGMP substrate more strongly than it binds to dGMP.

ΔH _f(A-8OG) = −24446.41, ΔH _f(A-GMP) = −24380.00, ΔH _f(B-8OG) = −19421.98, and ΔH _f(B-GMP) = −19354.72 kcal mol⁻¹