Table 2.

Kinetic parameters of the LTAaj's mutants for the retro‐aldol cleavage of l‐allo‐threonine and l‐β‐phenylserine. Conversion in the aldol reaction of glycine and benzaldehyde to synthesize l‐β‐phenylserine

Mutant	l‐allo‐threonine			l‐β‐phenylserine
	k cat, s−1	K m, mm	k cat/K m, s−1·m −1	k cat, s−1	K m, mm	k cat/K m, s−1·m −1	Aldol reaction, conv. %a
wt	8.67	0.5	1.7 × 104	60.5	3.7	1.6 × 104	25 (syn)
K199Rb	0.08	2.7	30	n.d.	n.d.		0
D168V	0.02	2.7	6.7	0.6	1.3	4 × 102	20 (syn)
D168Sb	0.42	1.2	350	0.83	4.1	2 × 102	22 (syn)
D168N	0.05	2.6	20	n.d.	n.d.		20 (syn)
R313H	2.3	28	80	0.32	5.2	62	21 (syn)
R171F	0.23	18	10	0.17	7	24	0
R171Q	0.47	69	6.8	0.2	17	11	< 5
C196T	13.3	0.5	2.6 × 104	84	3.7	2.2 × 104	25 (syn)
S198H	5.1	5.7	0.9 × 103	4.3	4.8	9 × 102	17 (syn)
H85F	0.05	11.5	4.5	0.3	4.6	63	9 (anti)
H85Y	0.01	14.8	0.7	0.2	3.8	50	7 (anti)
R231A	0.7	7.5	90	2.3	4.1	6 × 102	20 (syn)
N64E	0.3	5.7	60	0.08	1	80	26 (syn)
N64I	1	3.8	3 × 102	0.2	0.8	3 × 102	25 (syn)
G200S	13.6	0.2	6.1 × 104	74.4	2.1	3.5 × 104	24 (syn)
E138A	3.9	2.3	1.7 × 103	1.9	1.2	1.6 × 103	12 (syn)

^aReaction conditions: 50 mm benzaldehyde, 0.5 m glycine, 1 mg LTA, pH 8.0, 25°C, 24 h. e.e. > 99%; d.e. = 25–35% (the major isomer is given in parentheses).

^bAfter addition of PLP.