Table 2. Metal ion-binding sites of NQ-HaBLA classified based on ligand residues.

Chains generated by a crystal symmetry operator are indicated by an asterisk after the chain name. Square brackets indicate the chains involving the residues of the metal ion-binding sites. Parentheses indicate the locations of the metal ion-binding site. For example, (A, C) means that the metal ion-binding sites is located at the monomer surfaces of each chain A and chain C and (A/B) means that the metal ion-binding site is located at the interface between chain A and chain B.

			Bound metal ions
	Chelating atoms		Without soaking	Condition 1A	Condition 1B	Condition 1C	Condition 2A	Condition 2B
Metal ion-binding sites	Residue	Atom	200mM Na+, 200mM Ca2+	100mM Cs+, 200mM Ca2+	25mM Cs+, 75mM Na+, 200mM Ca2+	10mM Cs+, 90mM Na+, 200mM Ca2+	100mM Na+, 200mM Sr2+	100 mM Na+, 100mM Sr2+, 100mM Ca2+
Site 1	Asp56 [A]	O1	Ca2+ (A/C)
	Glu170 [C]	O1
	HOH 3	O
Site 2	Asp58 [C]	O1	Ca2+ (C/A*)	Ca2+ (C/A*)	Ca2+ (C/A*)	Ca2+ (C/A*)	Sr2+ (C/A*)
	Asp128 [A*]	O1
	HOH 35	O
Site 3	Asp85 [A]	O1	Ca2+ (A/B)	Ca2+ (A/B)	Ca2+ (A/B)	Ca2+ (A/B)
	Asp87 [A]	O1
	Asp187 [B]	O1
	HOH 12	O
Site 4	Asp124 [A]	O1	Ca2+ (A)		Ca2+ (A)	Ca2+ (A)
	HOH 35	O
Site 5	Asp199 [B]	O1	Ca2+ (B)	Ca2+ (A, B)	Ca2+ (B)	Ca2+ (B)
	HOH 23	O
Site 6	Asp219 [A, B, C]	O1	Ca2+ (A, B, C)	Ca2+ (A, B, C)	Ca2+ (A, B, C)	Ca2+ (A, B, C)	Sr2+ (A, B, C)	Sr2+ (A)
	Asp220 [A, B, C]	O1
	HOH 15	O
Site 7	Asp291 [A*, B, C*]	O1	Ca2+ (A/A*, B/B*, C/C*)	Ca2+ (A/A*, B/B*, C/C*)	Ca2+ (A/A*, B/B*, C/C*)	Ca2+ (A/A*, B/B*, C/C*)	Sr2+ (A/A*, B/B*, C/C*)	Ca2+ (B/B*)
	Glu295 [A*, B, C*]	O1
	Glu352 [A, B*, C]	O1
	HOH 14	O
Site 8	Gln186 [A, C]	O		Cs+ (A, C)	Cs+ (A, C)	Cs+ (A)
	Thr188 [A, C]	O
	Trp189† [A, C]	C2, C2, C3, C2, C3, C2
	HOH 01	O

^†The aromatic ring of Trp189 interacts with Cs⁺ by a cation interaction.