Table 2.

Substrate specificity of octopine synthase for amino acids and α-keto acids.

Amino Acid	α-keto acid	km (mM)	kcat (min-1)	Enzymatic Efficiency (kcat/km)	Relative activity (%)
L-Arginine	Pyruvate	3.5 ± 0.3	720	210	(100)
L-SMM	Pyruvate	0.31 ± 0.04	49	160	76
L-HCys	Pyruvate	8.9 ± 1.1	1600	180	86
L-Methionine	Pyruvate	27 ± 6	4700	170	81
L-Cysteine	Pyruvate	11 ± 3	670	61	29
L-Histidine	Pyruvate	2.0 ± 0.21	1200	600	286
L-Canavanine	Pyruvate	2.8 ± 0.5	1000	360	171
L-Ornithine	Pyruvate	3.0 ± 0.4	540	180	86
L-Lysine	Pyruvate	0.74 ± 0.08	130	178	85
L-Glutamine	Pyruvate	5.6 ± 0.6	780	140	67
L-Homoserine	Pyruvate	15 ± 3	1800	120	57
L-Glycine	Pyruvate	30 ± 6	1300	43	20
L-Homoarginine	Pyruvate	11 ± 2	410	37	18
L-Leucine	Pyruvate	11 ± 2	410	37	18
L-Serine	Pyruvate	12 ± 2	220	18	9
L-Alanine	Pyruvate	47 ± 14	340	7.2	3.4
L-Asparagine	Pyruvate	41 ± 13	220	5.4	2.6
L-Threonine	Pyruvate	976 ± 30	4600	4.7	2.2
L-Valine	Pyruvate	36 ± 5	170	4.7	2.2
L-Isoleucine	Pyruvate	70 ± 30	180	2.6	1.2
L-Glutamic acid	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Aspartic acid	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Tryptophan	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Tyrosine	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Phenylalanine	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Proline	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
L-Carnosine	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
D-Arginine	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
D-Methionine	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
D-SMM	Pyruvate	>1.5 × 106	<6.9 × 104	<0.6	<0.09
Arginine	Pyruvate	0.44 ± 0.07	561	1275	(100)
Arginine	α-ketobutyrate	6 ± 1	573	96	7.5
Arginine	Oxaloacetate	28 ± 4.5	1073	38	3
Arginine	Glyoxylate	22 ± 5	354	16	1.3
Arginine	α-ketoglutarate	>1.5 e+6 α	<6.9 e+4 α	>0.6 α	>0.09 α

Mean ± SD of n=3 enzymatic reactions.

^αDetection limit