Table 4.

Synthesis of nucleosides by T. thermophilus NPs^a

Enzyme	Acceptor	Feature	% Synthesis (mean ± SD)b
TtPNPI	HX	2,6-Dioxo	42.0 ± 0.5
	BI	Backbone only	ND
	DAP	2,6-Diamino	ND
TtPNPII	A	6-Amino	51.0 ± 0.4
	BI	Backbone only	ND
	DAP	2,6-Diamino	41.7 ± 1.5
TtPyNP	U	2,4-Dioxo	49.1 ± 1.3
	5-FC	2-Oxo,4-amino,5-fluoro	ND
	DFU	2,4-Difluoro	ND
	6-tFMeU	2,4-Dioxo,6-trifluoromethyl	ND
	FMPy	5-Fluoro,2-methoxy	ND
	5-IU	2,4-Dioxo,5-iodo	47.8 ± 1.1

^aThe transferred sugar moiety was a 2′-deoxyribose obtained by phosphorolysis of dUrd or Thd by TtPyNP. The reaction conditions for nucleoside synthesis by TtPNPI and TtPNPII were as follows: 5 mM dUrd and 2.5 mM acceptor nucleobase in sodium phosphate buffer (50 mM, pH 7.0), 10 μg of TtPyNP ml⁻¹, 5 μg of TtPNPI or TtPNPII ml⁻¹, and 30 min at 65°C. The reaction conditions for nucleoside synthesis by TtPyNP were as follows: 5 mM Thd and 2.5 mM acceptor in sodium phosphate buffer (50 mM, pH 7.0), 5 μg of TtPyNP ml⁻¹, and 30 min at 65°C. Acronyms: HX, hypoxanthine; BI, benzimidazole; DAP, 2,6-diaminopurine; A, adenine; U, uracil; 5-FU, 5-fluorouracil; DFU, 2-deoxy-2-fluorouracil; 6-tMeFU, 6-trifluoromethyluracil; FMPy, 5-fluoro-2-methoxy-4(1H)pyrimidinone; 5-IU, 5-iodouracil.

^bPercentage of free nucleobase converted into nucleoside with respect to the total amount of nucleobase used as a substrate. ND, not detected.