Table 2.

Kinetics of α-D-ribose 1-phosphate and 2-deoxy-α-D-ribose 1-phosphate synthesis by phosphopentomutase Thermus thermophilus HB27. Each reaction mixture (100 µL, 20 mM Tris∙HCl, pH 8.0) contained 1-mM adenine, 0.5 mM MnCl₂, and 0.25 µM α-D-glucose 1,6-bisphosphate, from 0.011 to 1.8 mM D-ribose 5-phosphate or 2-deoxy-D-ribose 5-phosphate, 0.02 or 0.05 µg TthPPM, and 0.5 µg TthPNPII. The reaction mixtures were incubated 2 min at 80 °C.

Substrate	KM, mM	Vmax, µmol/min·mg	kcat, s−1	kcat/KM, s−1·M−1
D-ribose 5-phosphate	0.19 ± 0.02	3.50 ± 0.40	2.50 ± 0.30	1.3 × 104
2-deoxy-D-ribose 5-phosphate	0.25 ± 0.04	0.48 ± 0.08	0.35 ± 0.06	1.4 × 103