Table 1. Examples of polar ratio in protein complexes.

Target	PDB p-p	Ratio p-p	Affinity	PDB p-sm	Ratio p-sm	Affinity	refs
IL-2	1Z92 (A:B)	0.35	10nM (Kd)	1PY2 (A)	0.21	60nM (IC50)	[27],[28]
Bcl-XL	2BZW (A:B)	0.19	6nM (Kd)	2YXJ (B)	0.08	0.6nM	[29]
MDM2	1YCR (A:B)	0.14	600nM (Kd)	1T4E (A)	0.03	67nM (Kd)	[30],[31]
XIAP	1G3F (A:B)	0.22		1TFT (A)	0.12		[32], [33]
ZipA	1F47 (B:A)	0.10	21.6uM (Kd)	1Y2F (A)	0.00	12uM (Kd)	[34],[35]
TNF	1TNF (AB:C)	0.30	-	2AZ5 (C&D)	0.12	13uM	[36], [37]
S100B	1DT7 (A:X)	0.34	-	3GK1 (A)	0.12		[38],[39]

Polar ratio is the number of polar contacts divided by the total [polar + apolar] number of contacts. These protein complexes are for proteins that bind to both protein partners (ratio p-p, left) and synthetic small molecules (ratio p-sm, right). The PDB code includes the interacting chains, for example 1TNF(AB:C) denotes chain A and B interacting with chain C of the TNF trimer, whereas 2AZ5 (C&D) denotes chains C and D interacting with the small molecule. When available, affinity measure and units is specified in table.