Table 1.

Kinetic Parameters of pNPG Catalysis for GUS Enzymes.

Loop Class	GUS	Optimal pH	kcat (s−1)	Km (mM)	kcat/Km (s−1mM−1)
L1	E. coli	7.4	120 ± 10a	0.13 ± 0.01a	920 ± 10a
L1	E. eligens	6.5	120 ± 8	0.223 ± 0.008	540 ± 20
L1	S. agalactiae	6.5	122 ± 3	0.17 ± 0.01	720 ± 30
L1	C. perfringens	6.5	57 ± 2	0.16 ± 0.02	360 ± 40
L1	F. prausnitzii	6.0	58 ± 4	2.2 ± 0.3	27 ± 2
L1	L. rhamnosus	4.5	10.0 ± 0.7	1.5 ± 0.1	6.7 ± 0.3
L1	R. gnavus	6.5	2.8 ± 0.3b	1.4 ± 0.2b	2.0 ± 0.1b
mL1	B. fragilis	5.0	22 ± 2	0.58 ± 0.09	39 ± 4
L2	B. uniformis	5.5	37 ± 2	0.54 ± 0.06	71 ± 6
mL2	P. merdae	5.5	0.088 ± 0.001	2.40 ± 0.07	0.0368 ± 0.0008
mL1,2	B. ovatus	5.0	0.48 ± 0.03b	1.38 ± 0.01b	0.34 ± 0.02b
NL	B. dorei	6.0	7.5 ± 0.4	1.4 ± 0.1	5.2 ± 0.5

Data are presented as the average of 3 biological replicates and errors are standard error of the mean (SEM). k_cat is catalytic rate; K_m is Michaelis constant; k_cat/K_m is catalytic efficiency. Crystal structures reported in this study are underlined. ^aData were previously reported in Wallace et al.¹⁷. ^bData are reported as apparent k_cat and K_m values.