. Author manuscript; available in PMC: 2017 Aug 16.

Published in final edited form as: Biochem J. 2017 Mar 7;474(6):1017–1039. doi: 10.1042/BCJ20161025

Table 3.

Relative catalytic activities (%) of GCYH-IB mutants.

Protein	Radiochemical^a	UV-vis^a
Wild-type	100	100
E152A	24.7	21.4
E243A	0.36	0.37
C149A	11.0	NA^b
C149S	17	2.7
H246A	2.0	0.74
H246D	72	3.0
H246Q	67	2.4
H246N	24	NA
H246K	5.0	NA

Activity reflects the relative initial velocities determined via the radiochemical and UV-vis time course assays, which quantify the formation of [¹⁴C]-HCO₂H and H₂NTP, respectively. Standard errors for the initial velocity measurements calculated from the radiochemical and UV-vis data varied from 2-8% and 2.5-10%, respectively.

NA indicates that no activity was detected. Detection limits were 0.25% of wild-type activity.