The major leucyl aminopeptidase of Trypanosoma cruzi (LAPTc) assembles into a homohexamer and belongs to the M17 family of metallopeptidases

Table 4 Inhibition pattern and cation dependence of LAPTc

Inhibitor	Enzymatic activity (% of control)^a
	No cation	Mn²⁺	Ca²⁺	Zn²⁺	Fe²⁺	Mg²⁺	Al³⁺	Co²⁺
10 mM EDTA	55	149	117	80	50	44	11	5
250 μM 1,10-phenanthroline	17	135	115	78	18	20	5	4
100 μM bestatin	3	ND^b	ND	ND	ND	ND	ND	ND
2 mM PMSF	100	ND	ND	ND	ND	ND	ND	ND
10 μM E-64	98	ND	ND	ND	ND	ND	ND	ND
10 μM TLCK	97	ND	ND	ND	ND	ND	ND	ND
1 mM leupeptin	99	ND	ND	ND	ND	ND	ND	ND
200 μM pepstatin A	102	ND	ND	ND	ND	ND	ND	ND

^a LAPTc was incubated with inhibitor before enzymatic assay at 37°C with Leu-AMC. Peptidase incubated with EDTA or 1,10-phenanthroline was dialyzed against reaction buffer prior to incubation with 20 μM Leu-AMC and 0.4 mM MnCl₂, CaCl₂, ZnCl₂, FeCl₂, MgCl₂, AlCl₃, or CoCl₂. Results represent means from three independent experiments carried out in triplicate. Standard deviations were less than 10%. ^b ND, not determined.

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