TABLE 2.

Hydroysis parameters of thiolester substrates for different PBPs

PBPa	kcat/Km (M−1 s−1) for:		Reference or source
	Bz-D-Ala-Thg	Bz-Gly-Thg
Class A
His*PBP1 (E. faecalis)	230 ± 15	430 ± 20	This work
PBP1a* (S. pneumoniae R6)	128	5.7	8
PBP2a* (S. pneumoniae R6)	220	NDb	9
PBP1* (M. leprae)	4,500	ND	26
Class B
PBP2x* (S. pneumoniae R6)	3,600	160	43
t-PBP3s* (E. hirae)	3,200	<20	1
PBP2b* (S. pneumoniae)	300	<20	1
PBP3* (E. coli)	100	20	2
LMM
PBP R61 (Streptomyces sp. strain R61)	100,000	430,000	7
PBP R39 (Actinomadura sp. strain R39)	10,000	336,000	7

^a*, soluble derivative of the wild-type protein; t-PBP3s, tryptic derivative of PBP3s.

^bND, not determined.