Table 3.

Phosphorolysis of nucleosides by T. thermophilus NPs^a

Enzyme	Nucleoside	Nucleobase features	Sugar moiety features	Mean (%) phosphorolysis ± SDb
TtPNPI	dIno	6-Oxo	2′-Deoxyribose	58.4 ± 0.6
	ACV	6-Oxo,2-amino	Open ring	ND
TtPNPII	dAdo	6-Amino	2′-Deoxyribose	34.0 ± 0.3
	ara-A	6-Amino	Arabinose	1.0 ± 0.1
TtPyNP	dUrd	2,4-Dioxo	2′-Deoxyribose	55.0 ± 1.1
	ara-U	2,4-Dioxo	Arabinose	3.2 ± 0.1
	AZT	2,4-Dioxo,5-methyl	3′-Azido-5′-phosphoribose	ND

^aReaction conditions: 2.5 mM nucleoside in sodium phosphate buffer (50 mM, pH 7.0), 5 μg of enzyme extract ml⁻¹, and 30 min at 65°C. Acronyms: dIno, 2′-deoxyinosine; ACV, acyclovir; dAdo, 2′-deoxyadenosine; ara-A, adenine-arabinoside; dUrd, 2′-deoxyuridine; ara-U, uracil-arabinoside; AZT, azidothymidine.

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