Table 2. Core metal ligands.

Native metals and their inner sphere ligands are listed along with interference assay data. Potential ligands under 3.0 Å for Mg²⁺ and 3.8 Å for K⁺ are listed. Inhibition column indicates if sulfur or nitrogen substitution of the oxygen ligand caused interference. Shaded regions indicate interference was rescued by addition of thiophilic metal ion addition. This is a biochemical signature suggestive of inner sphere metal ion coordination. Rate effect column indicates the rate decrease upon sulfur or amino substitution. Interference column indicates interference of polymerase incorporated phosphorothioates

metal	region	Azo	Tet	atom	dist (Å)	inhibition rescue	reference	rate effect	interference Azo, Tet	Tb3+ [14]
M1	J8/7	A172	A306	pro-SP	2.1	y	[24]	25-50
	J5/4	C88	C208	pro-SP	2.3	y	[24]	25-50
	3’-exon	A+1	A+1	pro-RP	2.3	y	[22,19]	1000		y
	5’-exon	dT-1	U-1	O3’	2.4	y	[19]	1000
	J8/7	G170	A304	pro-SP	2.5	y	[24]	2-5
M2 (rΩG)	3’-exon	A+1	A+1	pro-RP	1.9	y	[22,19]	1000		y
	J6/7	G128	A262	pro-SP	1.6	y	[25]	>10		y
	J8/7	A172	A306	pro-RP	2.0	y	[26,27,24]	25-50	6,6	y
		G206	G414	O2’	2.1	y	[20]	~30
		G206	G414	O3’	2.5	y	[21]	inactive
	J5/4	A87	A207	pro-SP	3.7	y	[24]	25-50
M3	P7	U173	U307	pro-RP	2.3	y	[27,26]		6,3
		A174	A308	pro-RP	2.1	y	[27,26]		6,2*
M5	J8/7	C171	U305	pro-RP	2.8	y	[27,26,24]	2-5	6,6
	J6/7	U126	C260	O2’	3.0	n	[27,26]
	P6	U124	U258	pro-SP	3.3	y	[25]	5-10
	J6/7	A127	A261	pro-RP	3.4	y	[27,26]		3*,0
M12	P6	U124	U258	pro-SP	2.1	y	[25]	5-10
	J8/7	C171	U305	pro-RP	2.3	y	[27,26]	2-5	6,6

^*indicates data set with soft metal rescue where data sets differ. Potential outer sphere M2 ligand is shown in italics.