TABLE 3.

pH dependence of Zn²⁺-MshB variants

MshBa,b	pKa1	pKa2	V/K at pH optimum	WT activity
			m−1s−1
WTc	7.4 ± 0.07	10.5 ± 0.06	48.2 ± 1.5	%
D15A		10.5 ± 0.13	0.091 ± 0.003	0.2
Y142A	7.1 ± 0.10		0.96 ± 0.03	2.0
Y142F	7.0 ± 0.05		0.65 ± 0.01	1.3
H144A	7.1 ± 0.10	10.5 ± 0.09	0.27 ± 0.01	0.6
D146A	7.2 ± 0.10	10.4 ± 0.10	0.18 ± 0.01	0.4

^a Apo-MshB was incubated with stoichiometric metal for 30 min prior to activity measurement.

^b Substrate 5 (WT, Y142F), 10 (Y142A), 20 (D15A, H144A), or 50 mm (D146A) GlcNAc.

^c Data adapted from Ref. 14.