Table III.

Maximal, pH independent values of the kinetic constants for catalysis by variants of HCA II measured by ¹⁸O exchange

Enzyme	kcatex/KeffSa (μM−1 s−1)	kBa (μs−1)
Wild type	120	0.8
Y7Fb	120	3.9
TS1	85	1.3
TS2	110	5.6
TS3	88	∼0.1
TS4	94	4.9
TS5	110	∼0.1

^aThe standard errors in these rate constants determined by fitting reactions (5) and (6) to the data of Figs S2 and S3 are in the range of 10–20%.

^bFrom Fisher et al. (2007a,b). Data at 10°C.