Table 1.
Structural characteristics and toxicity of r3FTXs and native 3FTXs.
| Protein | Disulfide-Linked Peptide | ||||||
|---|---|---|---|---|---|---|---|
| Toxin | Expected MW (Da) 1 | Observed MW (Da) | Toxicity | Secondary Structure 3 | Peptide Sequence | Mass Ion (m/z) | Linkage Site(s) |
| LNTX | 7815.66 | 7815.57 | LD50 2: 0.15 | 33.5% β-sheet | TWC26DAFC30SIR | 616.2 (2+) | C26-30 |
| (0.12–0.19) | 9.8% α-helix | C3FITPDITSK | 846.9 (7+) | C3-C14 | |||
| 10.5% Turn | DC14PNGHVC20YTK | C20-C41 | |||||
| VDLGC41AATC45PTVK | C45-C56 | ||||||
| TGVDIQC56C57STDNC62NPFPTR | C57-C62 | ||||||
| rLNTX | 7872.68 | 7872.58 | LD50: 0.21 | 34.7% β-sheet | TWC27DAFC31SIR | 616.2 (2+) | C27-31 |
| (0.18–0.24) | 9.2% α-helix | C4FITPDITSK | 846.9 (7+) | C4-C15 | |||
| 9.9% Turn | DC15PNGHVC21YTK | C21-C42 | |||||
| VDLGC42AATC46PTVK | C46-C57 | ||||||
| TGVDIQC57C58STDNC63NPFPTR | C58-C63 | ||||||
| sNTX | 6945.04 | 6944.97 | LD50: 0.23 | 54.5% β-sheet | LEC3HNQQSSQTPTTTGC17SGGETNC24YK | 899.9 (6+) | C3-C24 |
| (0.17–0.26) | 0.0% α-helix | GC41GC43PSVK | C17-C41 | ||||
| 7.4% Turn | NGIEINC54C55TTDR | C43-C54 | |||||
| C60NN | C55-C60 | ||||||
| rsNTX | 7001.06 | 7000.99 | LD50: 0.25 | 53.4% β-sheet | GLEC4HNQQSSQTPTTTGC18SGGETNC25YK | 909.3 (6+) | C4-C25 |
| (0.19–0.33) | 0.0% α-helix | GC42GC44PSVK | C18-C42 | ||||
| 8.1% Turn | NGIEINC55C56TTDR | C44-C55 | |||||
| C61NN | C56-C61 | ||||||
| CTXA3 | 6734.43 | 6735.36 | IC50 4: 1.93 | 54.5% β-sheet | LKC3NK | 701.9 (2+) | C3-C21 |
| (1.67–2.23) | 0.0% α-helix | NLC21YK | |||||
| 7.4% Turn | TC14PAGK | 561.4 (5+) | C14-C38 | ||||
| GC38IDVC42PK | C42-C53 | ||||||
| YVC53C54NTDR | C54-C59 | ||||||
| C59N | |||||||
| rCTXA3 | 6791.45 | 6792.38 | IC50 4: 2.02 | 53.4% β-sheet | GLKC4NK | 487.3 (3+) | C4-C22 |
| (1.88–2.15) | 0.0 % α-helix | NLC22YK | |||||
| 8.1% Turn | TC15PAGK | 561.5 (5+) | C15-C39 | ||||
| GC39IDVC43PK | C43-C54 | ||||||
| YVC54C55NTDR | C55-C60 | ||||||
| C60N | |||||||
1 Oxidized cysteine was considered in the calculation of the expected MW of the protein. 2 LD50 (μg/g, toxin amount/mouse body weight) indicates the amount of toxin (i.p.) that caused half of the ICR mice (19–22 g body weight, n = 6) death, which were calculated by the trimmed Spearman–Karber method. Values in brackets represent 95% confidence intervals. 3 Estimation by the BeStSel web server [30]. 4 The toxicity of cardiotoxin was expressed as the IC50 value (μg/g) corresponding to the concentration of toxin that caused half of human promyeloblast cells (HL-60 cell, 1 × 105/100 μL per toxin) lysis as described in a previous study [33].