TABLE 4.

Comparison of the estimates of accessible surface area and the buried surface area in the GIPr ECD-Gipg013 Fab and GIPr ECD-GIP(1–42)_{complexes using PISA}

Complex	Accessible surface area	Buried surface area	ΔGinta	ΔGdissb
	Å2	Å2	kcal/m	kcal/m
GIPr ECD- Gipg013 Fab, A-PQc	23,740	5210	−34.0	4.0
GIPr ECD- Gipg013 Fab, B-CDc	24,300	5110	−39.5	7.1
GIPr ECD-GIP(1–42), PDB code 2QKH	7920	1250	−7.9	−0.3

^a Solvation free energy gain upon formation of the assembly, in kcal/m.

^b Free energy of assembly dissociation, in kcal/m, where ΔG^diss > 0 indicates a thermodynamically stable complex.

^c A-PQ and B-CD denote the complex chains in the asymmetric unit of the crystal structure of GIPr ECD- Gipg013 Fab, where A and B are GIPr ECDs, and PQ and CD are Fab fragments of Gipg013. When the interface of heavy and light chains of Gipg013 Fab is excluded in the complex for free energy calculations, complex 1 (A-PQ) has a ΔG^int and ΔG^diss of −11.9 and 2.4, respectively. Complex 2 (B-CD) has a ΔG^int and ΔG^diss of −12.1 and 2.2, respectively, indicating a stable complex compared with GIPr ECD-GIP(1–42).