. 2018 Feb 21;9:248. doi: 10.3389/fmicb.2018.00248

Table 2.

Kinetic parameters of NDM-20 and NDM-5^a.

β-Lactam	NDM-20^b			NDM-5^b			k_cat/K_m (μM^-1 s^-1) ratio for NDM-20/NDM-5
	K_m (μM)	k_cat (s^-1)^b	k_cat/K_m (μM^-1 s^-1)	K_m (μM)	k_cat (s^-1)^b	k_cat/K_m (μM^-1 s^-1)
Ampicillin	167 ± 1.9	92 ± 11	0.55	425 ± 27	103 ± 10	0.24	2.29
Amoxicillin	391 ± 35	15 ± 0.87	0.04	561 ± 17	25 ± 2.6	0.04	1.00
Penicillin G	313 ± 17	113 ± 2.1	0.36	283 ± 41	99 ± 5.5	0.35	1.03
Aztreonam	NH^c	NH	NH	NH	NH	NH	NH
Cefotaxime	15 ± 0.18	18 ± 0.05	1.2	20 ± 0.89	19 ± 1.4	0.95	1.26
Cefoxitin	39 ± 0.34	11 ± 0.01	0.28	66 ± 3.3	11 ± 0.45	0.17	1.65
Ceftazdime	107 ± 8.1	19 ± 1.4	0.18	109 ± 12	19 ± 0.53	0.17	1.06
Ertapenem	278 ± 9.1	127 ± 5.5	0.46	124 ± 3.8	88 ± 3.2	0.71	0.65
Imipenem	377 ± 25	147 ± 3.3	0.39	302 ± 14	128 ± 1.2	0.42	0.93
Meropenem	362 ± 12	160 ± 4.9	0.44	257 ± 12	128 ± 0.65	0.50	0.88

^aThe proteins were initially modified with a His-tag, which was removed after purification.

^bK_m and k_cat values are means ± standard deviations from three independent experiments.

^cNH, no hydrolysis was detected under conditions with substrate concentrations up to 1 mM and enzyme concentrations up to 700 nM.