Table 3. Tunnels in CYP2C9.

Tunnel1)	Residues defining entrance (1R9O1)2)	Residues defining entrance (1R9O2)2)	Lining secondary structure3)
2a	F69, K72, P101	K72, P101, S220, P221	β1 sheet, FG, BC loops
2b	K72, I74, R97, I99	K72, I74, R97, I99	β1, β2 sheets, BC loop
2c	A106, R108, V237, E288	A106, R108, V237, E288	G, I helices, BC loop
2ac	P101, A106, P221, H230	L102, A106, I222, H230	G helix, BC loop
2e	G98, P101, A106, G109	G98, P101, A106, G109	BC loop
2f	P37, I45, N218, P221	I42, I47, I215, P211	FG loop, N-terminal coil
S (solvent)	C206, E300, R307, F476	C206, E300, R307, F476	F, E helices, β4 sheet

1. Nomenclature as in [20].

2. The tunnel entrance was defined as the geometric center of the Cα atoms of the residues listed.

3. The original secondary structure nomenclature defined for the bacterial P450s [26] was adapted to CYP2C9.