Table 6. The most common ternary inter-chain anion–π–π interactions in proteins. Triads of interacting residues and their occurrences in number (amount), percentage (%), and residues' representativities for each distinct anion (%A^–), central (%π_c), and terminal (%π_t) π-systems. The expected amount of each interaction pair, according to its relative abundance, and the statistical significance are shown (Methods). Statistical significance is denoted with ** for p-value < 0.01, and *** for p-value < 0.001.

Interaction	Amount (expected)	%	%A–	%πc	%πt
Glu–Tyr–Phe	46 (34)	13.0	22.4	42.2	24.2
Asp–Trp–Phe	41 (15)***	11.6	27.5	63.1	21.6
Glu–Phe–Phe	38 (30)	10.7	18.5	39.2	20.0
Glu–His–His	23 (8)**	6.5	11.2	27.7	39.0
Asp–Phe–Phe	22 (22)	6.2	14.8	22.7	11.6
Asp–Tyr–Phe	21 (25)	5.9	14.1	19.3	11.1
Glu–Phe–Tyr	20 (11)	5.6	9.8	20.6	28.2
Glu–Tyr–Tyr	14 (13)	4.0	6.8	12.8	19.7
Glu–His–Tyr	12 (10)	3.4	5.9	14.5	16.9
Asp–His–Trp	10 (3)	2.8	6.7	12.0	29.4