Table 1.

β-lactamase homologs with open Ω-loop pockets display increased catalytic efficiencies against benzylpenicillin

Protein	Ω-Loop pocket open population (%)	kcat/KM (sec−1 ⋅ µM−1)	kcat (sec−1)	KM (µM−1)
Penicillin-binding proteins	N/A – no Ω-loop	N/A – cannot deacylate penicillin	N/A	N/A
GNCA β-lactamase	N/A – no Ω-loop pocket	0.40 ± 0.02	6.1 ± 0.1	15.1 ± 0.7
MTB β-lactamase	N/A – no Ω-loop pocket	0.64 ± 0.01	47.0 ± 0.9	72.9 ± 0.8
CTX-M-9 β-lactamase	0.023 ± 0.008 (21)	9 ± 2	250 ± 20	27 ± 4
TEM β-lactamase*	1.1 ± 0.2 (21)	15.2 ± 0.6	411 ± 5	27 ± 1

N/A, not applicable.

^*Including an S243C mutation needed for thiol-labeling measurements.