. Author manuscript; available in PMC: 2010 Apr 28.

Published in final edited form as: Biochemistry. 2009 Apr 28;48(16):3658–3668. doi: 10.1021/bi802339c

Table 3.

Comparison of Pre-Steady State Kinetic Rates (forward and reverse)^a and On-Enzyme K_eq^b for F159W-Leuko- and native PNPs

	F159W-Leuko-PNP (Ino-HX)			Native PNP (Guo-Gua)
Temp	k_(chem)f s⁻¹	k_(chem)r s⁻¹	K_eq	k_(chem)f s⁻¹	k_(chem)r s⁻¹	K_eq
1 °C	75	7	11.2	9	39	0.23
3 °C	79	9	8.8	12	42	0.28
5 °C	83	10	8	15	44	0.34
8 °C	100	18	5.4	22	49	0.44
11 °C	115	26	4.4	31	54	0.57
15 °C	135	44	3.0	50	61	0.81
20 °C	175	82	2.12	89	71	1.25
25 °C	209	152 (108 ± 30)^c	1.4	154	80	1.92
30 °C	255	275	0.93	262	93	2.81
37 °C	334	608	0.55	536	111	4.82

Determined by stopped-flow fluorescent studies (in the temperature range between 1 to 20 °C or extrapolated from the Arrhenius equation above this temperature range) for F159W-Leuko-PNP with inosine/hypoxanthine and native PNP with guanosine/guanine as substrates for the forward (f)/reverse (r) reactions, respectively.

Calculated from the ratio between k_(chem)f to k_(chem.)r.

Determined at room temp (22 °C) by quench-flow for F159W-Leuko-PNP with hypoxanthine and ribose 1-phosphate.