Table 1.
Biochemical properties of nepenthesins from various carnivorous and crop plants.
| Source (Species) | Proteases | Molecular Weight (kDa) | Specific Activity | Substrates | Optimum | Inhibitors | Substrate Specificity | References | ||
|---|---|---|---|---|---|---|---|---|---|---|
| pH | T (°C) | Substrates | Cleavage Specificity | |||||||
| Nepenthes sp. | Nepenthesin | n.d. | 0.55 U mL−1 | Casein | 2.8 | 40 | n.d. | Peptides (8) | Leu-Asp, Ser-Asp, Thr-Asp, Ala-Ala, Tyr-Asp | [21] |
|
N. maxima
N. rafflesiana N. ampullaria N. x dyeriana N. x mixta Drosera peltata |
Nepenthesin | n.d. | n.d. | Casein | 3.0 | 40 | n.d. | Peptides (6) | Asp-Glu, Asp-Ala, Ala-Ala, Lys-Arg | [22] |
| Nepenthes sp. | Nepenthesin | n.d. | n.d. | Casein | 2.9 | 40 | n.d. | n.d. | n.d. | [48] |
| N. macfarlanei | Nepenthesin I Nepenthesin II |
59.00 21.00 |
n.d. n.d. |
Bovine fibrin Bovine serum albumin Horse-heart cytochrome c |
n.d. n.d. 2.2 |
37 37 37 |
Pepstatin | Horse-heart cytochrome c | Lys-Ala, Glu-Asp, Glu-Thr, Lys-Thr, Gly-Gly, Leu-Phe | [6] |
| N. distillatoria | Nepenthesin I Nepenthesin II |
51.00 45.00 |
874 U mg−1 809 U mg−1 |
Acid-denatured haemoglobin | 2.6 2.6 |
55 45 |
Pepstatin, DAN | Oxidized insulin B chain | Phe-Phe, Glu-Ala, Leu-Cya, Leu-Tyr, Tyr-Leu | [23] |
|
N. alata,
Cephalotus follicularis D. muscipula D. capensis |
Nepenthesin I Nepenthesin II |
n.d. n.d. |
n.d. n.d. |
Haemoglobin Haemoglobin Oxidized insulin B chain |
2.5 3.0 3.5 |
47–57 60 47 |
Pepstatin | Oxidized insulin B chain | Leu-Tyr, Phe-Phe, Glu-Ala, Ala-Leu, Tyr-Leu, Tyr-Thr, Lys-Ala, Gly-Phe, | [25] |
| N. alata | Nepenthesin I Nepenthesin IIa Nepenthesin IIb |
n.d. n.d. n.d. |
n.d. n.d. n.d. |
Haemoglobin | n.d. n.d. n.d. |
n.d. n.d. n.d. |
n.d. n.d. n.d. |
n.d. n.d. n.d. |
n.d. n.d. n.d. |
[43] |
| N. gracilis | Nepenthesin 1 | 43.73 | n.d. | Haemoglobin Myoglobin |
2.5 n.d. |
50–60 n.d. |
n.d. | n.d. | n.d. | [42,49] |
| N. mirabilis | Nepenthesin I Nepenthesin II |
n.d. 45.00 |
n.d. n.d. |
PFU-093 (FRET peptide substrate) | 8.0 8.0 |
42 42 |
Pepstatin A | n.d. | n.d. | [50] |
| N. alata | Nepenthesin I Nepenthesin II |
n.d. n.d. |
n.d. n.d. |
PFU-093 (FRET peptide substrate) | 8.0 8.0 |
42 42 |
Pepstatin A | n.d. | n.d. | |
|
N. reinwardtiana
N. distillatoria N. eymae N. wittei N. hookeriana N. boschiana N. maxima |
Nepenthesin I Nepenthesin II |
n.d. n.d. |
n.d. n.d. |
PFU-093 (FRET peptide substrate) | 8.0 8.0 |
42 42 |
Pepstatin A | n.d. | n.d. | |
| N. gracilis * | Nepenthesin I Nepenthesin II |
n.d. 37.50 |
n.d. n.d. |
Haemoglobin | 2.5 2.5 |
50 55 |
n.d. | XRCC4, XLF, PNK, BRCT, myoglobin | Ser-Ilu/Pro/Thr//Phe, Glu-Glu, Leu-Tyr, Phe-Phe, Glu-Ala, Ala-Leu | [44] |
| N. rafflesiana | Nepenthesin-1 Nepenthesin-2 Nepenthesin-3 Nepenthesin-4 Nepenthesin-5 |
47.11 46.63 49.09 48.99 48.81 |
n.d. n.d. n.d. n.d. n.d. |
None | n.d. n.d. n.d. n.d. n.d. |
n.d. n.d. n.d. n.d. n.d. |
n.d. | n.d. | n.d. | [51] |
| H. vulgare | Nepenthesin-1 (HvNEP-1) | 48.90 | n.d. | Aspergillus ficuum phytase | 5.0 | 40 | Pepstatin A | n.d. | n.d. | [52] |
n.d.: not determined; kDa: kilo Dalton; T: temperature; FRET (fluorescent resonance energy transfer). For N. gracilis * nepenthesin I and II, 43 potential cleavage sites were identified but a small list of them is presented in the table. Two columns of substrates are indicated in the table. The first column of substrates was used for the determination of optimum condition for enzymatic activity, whereas substrates in the second column were used for enzyme-specific activity analysis. Peptide (6)/peptide (8) is to denote the number of specific peptide fragments used in the studies.