Table 1.

The kinetic data (K_m, k_cat/K_m, k_cat) for selected ACC substrates of N. mengitides aminopeptidase N (each compound was formally assigned to one of four groups in relation to its characteristic structural features), nd – not determined.

Group	Code	Km [μM]	kcat/Km [s−1M−1]	kcat [s−1]
A (linear, non-substituted)	Gly	>250	nd	nd
	L-Ala	174.7 ± 1.6	163 000 ± 3 000	28.4 ± 1.0
	L-Abu	161.6 ± 1.1	85 000 ± 7 000	13.8 ± 0.1
	L-propargylGly	121.3 ± 2.3	63 000 ± 2 000	7.74 ± 0.25
	L-Nva	28.8 ± 0.8	116 000 ± 2 000	3.33 ± 0.09
	L-allylGly	59.7 ± 2.7	82 000 ± 3 000	4.90 ± 0.16
	L-Nle	52.8 ± 6.0	52 000 ± 4 000	2.72 ± 0.18
	L-Met	80.7 ± 0.8	74 000 ± 2 000	5.99 ± 0.18
B (hydrophobic, branched aliphatic and aromatic)	L-Leu	85.4 ± 0.5	40 000 ± 1 000	3.45 ± 0.02
	L-neopentylGly	61.0 ± 1.6	27 000 ± 1 000	1.64 ± 0.10
	L-hLeu	56.9 ± 1.8	46 000 ± 1 000	2.65 ± 0.08
	L-Cha	121.9 ± 1.0	31 000 ± 1 000	3.84 ± 0.04
	L-hCha	41.4 ± 1.3	77 000 ± 3 000	3.19 ± 0.13
	L-Phe	>250	nd	nd
	4-Cl-L-Phe	149.1 ± 2.6	34 000 ± 1 000	5.05 ± 0.11
	4-Br-L-Phe	>250	nd	nd
	L-hPhe	100.8 ± 0.6	129 000 ± 1 000	13.0 ± 0.1
	L-Igl	48.9 ± 2.2	35 000 ± 2 000	1.72 ± 0.08
	L-2-Nal	50.7 ± 8.9	51 000 ± 7 000	2.6 ± 0.27
C (aliphatic, heteroatom terminated)	L-hSer	79.2 ± 6.9	79 000 ± 5 000	6.23 ± 0.67
	3-OH-L-Pro	57.2 ± 2.7	21 000 ± 2 000	1.19 ± 0.07
	L-Gln	>250	nd	nd
	L-Lys	88.7 ± 1.2	69 000 ± 2 000	6.15 ± 0.31
	L-Arg	64.1 ± 1.2	205 000 ± 7 000	13.1 ± 0.6
	L-Arg(NO2)	60.4 ± 4.8	120 000 ± 2 000	7.25 ± 0.20
	L-hArg	27.7 ± 2.3	312 000 ± 23 000	8.63 ± 0.59
D (heteroatom containing aromatic and heteroaromatic)	L-Tyr	46.4 ± 2.5	36 000 ± 2 000	1.66 ± 0.05
	L-hTyr	47.4 ± 1.6	270 000 ± 11 000	12.7 ± 0.6
	L-hSer(Bzl)	146.8 ± 7.9	28 000 ± 1 000	4.16 ± 0.13
	L-Asp(Bzl)	117.4 ± 4.0	31 000 ± 1 000	3.64 ± 0.05
	L-Glu(Bzl)	50.6 ± 2.7	111 000 ± 5 000	5.60 ± 0.28
	6-OBzl-L-Nle	59.9 ± 2.8	54 000 ± 1 000	3.24 ± 0.03
	L-Abu(Bth)	30.3 ± 4.8	173 000 ± 28 000	5.25 ± 0.85