Table 1. Results Summary Regarding Sequence and Length Dependence of Initiation Efficiency on Oligonucleotide Extension with TdT Polymerase and dTTP for Various Types of Initiator Chemistries^a.

		sequence motifs (5′→3′) for 10% highest/lowest signal					most/least efficiently extended substrate
	normalized average signalb		dimers	trimers	tetramers	pentamers	sequence	corresponding normalized signald
d-DNA 3′-OH	0.652	highest	G _	_ G G	_ _ _ _	_ _ _ _ _c	TTCAT	1.000
		lowest	T _	_ _ T/C	_ _ _ C	_ _ _ _ C	TAGAC	0.315
2′OMe-RNA 3′-OH	0.086	highest	_ _	_ G/A C/A	_ _ G/A C/A	_ _ _ G/A C/Ac	GGUGC	0.264
		lowest	U _	U U U/G	_ _ U G/U	_ _ U U G/U	UGUUG	0.018
l-DNA 5′-OH	0.021	highest	T _	T T _	T T _ _	T T _ _ _c	TTAAA	0.102
		lowest	_ _	_ G _	A G _ _	A G G _ _	AGT	0.004
HEG	0.083	n.s.	n.s.	n.s.	n.s.	n.s.	(HEG)2	0.125
d-DNA 5′-OH	0.002	n.e.	n.e.	n.e.	n.e.	n.e.	n.e.	n.e.

^a“_”, no distinct nucleotide occurring at higher frequency at this position; n.s., no sequence dependence; n.e., no extension.

^bFluorescent signal intensities averaged over all lengths and sequences, then normalized to highest signal intensity (1 = d-DNA 3′-OH “TTCAT”).

^cInitiator length showing highest fluorescent signal for extension.

^dFluorescent signal intensity of best or worst sequence for initiation, respectively, normalized to highest signal intensity.