TABLE 1.

Steady-state kinetic constants measured for Salmonella serovar Typhimurium AEPT at pH 8.5 and 25°C using alternate substrates

NH3 acceptor	NH3 donor	Km of NH3 acceptor (mM)	Km of NH3 donor (mM)	kcat (s−1)	kcat/Km of NH3 donor (M−1 s−1)
P-Ald	l-Alaa	0.09 ± 0.01c	1.4 ± 0.3d	9.3	6,600
α-Ketoglutaratei	l-Alaa	120e	0.0165 ± 0.0002f	0.025	1,500
P-Pyrj	l-Alaa	No activity	No activity	≤10−4
Oxaloacetate	l-Alaa	No activity	No activity	≤10−4
P-Ald	l-Aspb	0.66 ± 0.07g	9 ± 2h	0.029	3.2
α-Ketoglutaratek	l-Aspb	0.9 ± 0.4g	1.6 ± 0.2f	0.050	31
P-Pyr	l-Aspb	No activity	No activity	≤10−4
α-Ketoglutaratel	AEP	No activity	No activity	≤10−4

^aThe LDH/NADH coupled assay was used.

^bThe MDH/NADH coupled assay was used.

^cThe K_m of P-Ald and was measured with 20 mM l-Ala.

^dThe K_m of l-Ala was measured with 2.5 mM P-Ald.

^eThe estimated K_m of α-ketoglutaric acid was measured with 1 mM l-Ala.

^fThe K_ms of l-Ala and l-Asp were measured with 20 mM α-ketoglutaric acid.

^gThe K_ms of P-Ald and α-ketoglutarate were measured with 20 mM l-Asp.

^hThe K_m of l-Asp was measured with 5.0 mM P-Ald.

ⁱGlutamate-pyruvate transaminase activity (EC 2.6.1.2.).

^jP-Pyr, phosphonopyruvate.

^kAspartate transaminase activity (l-aspartate-2-oxoglutarate transaminase; l-aspartate-2-oxoglutarate transaminase; EC 2.6.1.1).

^lThe activity was measured in the direction of P-Ald formation as described in Materials and Methods.