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. Author manuscript; available in PMC: 2013 Feb 28.
Published in final edited form as: Biochemistry. 2012 Feb 16;51(8):1658–1668. doi: 10.1021/bi201899b

Table 4.

Kinetic parameters for cleavage of KDPGal and (R)-KHPB catalyzed by E. coli KDPG aldolase mutantsa and the enantiomeric selectivity ratio

Enzyme kcat
s−1 		KM
mM		 kcat/KMM−1s−1 Stereoselectivity ratiob
KDPGal
Wild-type c 0.0063 ± 0.0001 0.10 ± 0.01 61 ± 3 14,000
T161S 0.23 ± 0.02 0.3 ± 0.05 770 ± 90 710
S184L c 0.0026 ± 0.0001 0.95 ± 0.17 2.7 ± 0.4 78,000
T161S/S184L 0.0060 ± 0.0008 1.0 ± 0.1 6.5 ± 0.7 26,000
R-KHPB d
Wild-type ---- > 50 0.01 ± 0.003 33,000
T161S/S184F ---- > 50 0.017 ± 0.008 3,600,000
T161S/S184L ---- > 50 0.03 ± 0.004 5,000,000
a

The kinetic parameters were measured as described in Table 1.

b

The stereoselectivity ratio is defined as [(kcat/KMKDPG)/(kcat/KMKDPGal)] or [(kcat/KMS-KHPB)/(kcat/KMR-KHPB)] respectively. Values for kcat/KMKDPG and kcat/KMS-KHPB are listed in Table 1.

c

These data were previously published.(26)

d

The initial velocity is linearly dependent on the concentration of R-KHPB up to 50 mM, allowing measurement of only the value of kcat/KM.