Table 1.

List of GTP analogs used for the enzymatic synthesis of modified 5′ cap structures

GTP analogs				VCE				PBCVCE
				GTase (GMP-incorporation)		MTase (N7-methylation)		GTase
Modified moiety	Abbreviation	Str. #	Name	Previous reports	This research	Previous reports	This research	[19]
Base	m7GTP	1	N7-Methylguanosine-5′-triphosphate	No [20]	Yes	-	-	No
	m1GTP	2	N1-Methylguanosine-5′-triphosphate	-	Yes	-	No	Yes
	m6GTP	3	O6-Methylguanosine-5′-triphosphate	-	Yes	-	No*	Yes
	s6GTP	27	6-Thioguanosine-5′-triphosphate	Yes [23]	-	Yes [23]	-	Yes
	ms6GTP	28	6-Methylthioguanosine-5′-triphosphate	-	-	-	-	Yes
	deaza7GTP	4	7-Deazaguanosine-5′-triphosphate	-	No	-	-	No
	thienoGTP	5	Thienoguanosine-5′-triphosphate	-	No	-	-	-
	oxo8GTP	29	8-Oxoguanosine-5′-triphosphate	-	-	-	-	No
	Br8GTP	30	8-Bromoguanosine-5′-triphosphate	-	-	-	-	Yes
	I8GTP	31	8-Iodoguanosine-5′-triphosphate	-	-	-	-	Yes
	Cl6GTP	6	2-Amino-6-chloropurineriboside-5′-triphosphate	-	Yes	-	No	Yes
	Cl6PRTP	32	6-Chloropurineriboside-5′-triphosphate	-	-	-	-	No
	isoGTP	7	Isoguanosine-5′-triphosphate	-	No	-	-	-
	ATP	8	Adenosine-5′-triphosphate	No [20]	No		-	No
	a2ATP	9	2-Aminoadenosine-5′-triphosphate	-	No	-	-	No
	a2m6ATP	10	N6-Methyl-2-aminoadenosine-5′-triphosphate	-	No	-	-	-
	ITP	11	Inosine-5′-triphosphate	-	Yes	-	Yes	Yes
	s6ITP	33	6-Thioinosine-5′-triphosphate	-	-	-	-	No
	ms6ITP	34	6-Methylthioinosine-5′-triphosphate	-	-	-	-	No
	XTP	12	Xanthosine-5′-triphosphate	-	No	-	-	No
	CTP	35	Cytidine-5′-triphosphate	No [20]	-	-	-	-
	UTP	36	Uridine-5′-triphosphate	No [20]	-	-	-	-
	RTP	37	Ribavirin-5′-triphosphate	Yes [22]		No [22]
Ribose	dGTP	13	2′-Deoxyguanosine-5′-triphosphate	Yes [20]	Yes	Yes [20]	Yes	No
	d3′GTP	38	3′-Deoxyguanosine-5′-triphosphate	-	-	-	-	Yes
	ddGTP	14	2′,3′-Dideoxyguanosine-5′-triphosphate	-	No	-	-	No
	araGTP	15	Araguanosine-5′-triphosphate	-	Yes	-	Yes	-
	fGTP	16	2′-Fluoro-2′-deoxyguanosine-5′-triphosphate	-	Yes	-	Yes	Yes
	Om2′GTP	17	2′-O-Methylguanosine-5′-triphosphate	-	Yes	-	Yes	No
	Om3′GTP	18	3′-O-Methylguanosine-5′-triphosphate	-	Yes	-	Yes	Yes
	NH22′GTP	19	2′-Amino-2′-deoxyguanosine-5′-triphosphate	-	Yes	-	Yes	-
	NH23′dGTP	20	3′-Amino-2′,3′-dideoxyguanosine-5′-triphosphate	-	Yes	-	Yes	-
	N32′GTP	21	2′-Azido-2′-deoxyguanosine-5′-triphosphate	-	Yes	-	Yes	-
	N33′dGTP	22	3′-Azido-2′,3′-dideoxyguanosine-5′-triphosphate	-	Yes	-	Yes	-
	Opp3′GTP	23	3′-(O-Propargyl)-GTP	-	Yes	-	Yes	-
	Ant3′(/2′)GTP	39	3′(/2′)-O-Anthraniloyl-GTP	Yes [24]	-	Yes [24]	-	-
	Mant3′(/2′)GTP	40	3′(/2′)-O-(N-methylanthraniloyl)-GTP	No [24]	-	-	-	-
	DTB2′GTP	41	2′-Desthiobiotin-GTP	No [25]	-	-	-	-
	DTB3′GTP	42	3′-Desthiobiotin-GTP	Yes [25]	-	-	-	-
	EDA2′/3′GTP	24	2′/3′-O-(2-Aminoethyl-carbamoyl)-guanosine-5′-triphosphate	-	Yes	-	-	-
Base & ribose	m2dGTP	25	N2-Methyl-2′-deoxyguanosine-5′-triphosphate	-	No	-	-	-
	Ant3′(/2′)m7GTP	43	3′(or 2′)-(O-Anthraniloyl)-N7-methyl-GTP	Yes [24]	-	-	-	-
Phosphate	GTPαS	26	Guanosine-5′-O-(1-thiotriphosphate)	-	Yes	-	Yes	-

Results from this study and previous reports are summarized. The numbers in the column ‘Structure’ correspond to Figure 1b (#1-#26) and Supplementary Figure S1 (#27-#43). ‘Yes’, ‘No’, and ‘-’ mean ‘can be capped’, ‘cannot be capped’, and ‘not tested’, respectively. ‘3′(/2′)’ in #39, #40 and #43 indicates that molecules with a modification at 3′ (65%) or 2′ (35%) are included. See also ‘Discussion’ about MTase activity on #3 (m⁶GTP).