Peptide name : Vibi E

Source/Organism : Alpine violet, Viola biflora

Linear/Cyclic : Not found

Chirality : L

Peptide length: 30

C-terminal modification: Not found

N-terminal modification : Free

Non-natural peptide information: None

Assay type : Not specified

Assay time : Not found

Activity : Not found

Cell line : Not found

Cancer type : Lung cancer

Other activity : Not found

Amino acid composition bar chart :

Molecular mass : 3105.6732 Dalton

Aliphatic index : 0.876

Instability index : 27.7633

Hydrophobicity (GRAVY) : 0.8167

Isoelectric point : 5.9611

Charge (pH 7) : -0.2985

Aromaticity : 0.066

Molar extinction coefficient (cysteine, cystine): (6990, 7365)

Hydrophobic/hydrophilic ratio : 2.33333333

hydrophobic moment : 0.2146

Missing amino acid : R,H,Q,M,F,D

Most occurring amino acid : C

Most occurring amino acid frequency : 6

Least occurring amino acid : E

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.1, 0.3, 0.3)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CS)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H](NC(=O)[C@H](CS)NC(=O)[C@H](CO)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](C)NC(=O)[C@H](CS)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)CN)[C@@H](C)CC)C(C)C)[C@@H](C)CC)[C@@H](C)O)C(C)C)[C@@H](C)O)C(=O)NCC(=O)N[C@@H](CS)C(=O)NCC(=O)N[C@@H](CS)C(=O)N[C@@H](CO)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](CCCCN)C(=O)N[C@H](C(=O)N[C@@H](CS)C(=O)N[C@@H](Cc1ccc(O)cc1)C(=O)N[C@@H](CC(N)=O)C(=O)O)C(C)C

1 : Herrmann A, et al. The alpine violet, Viola biflora, is a rich source of cyclotides with potent cytotoxicity. Phytochemistry. 2008; 69:939-52. doi: 10.1016/j.phytochem.2007.10.023

Paper title : The alpine violet, Viola biflora, is a rich source of cyclotides with potent cytotoxicity.

Doi : https://doi.org/10.1016/j.phytochem.2007.10.023

Abstract : The cyclotides are currently the largest known family of head-to-tail cyclic proteins. The complex structure of these small plant proteins, which consist of approximately 30 amino acid residues, contains both a circular peptide backbone and a cystine knot, the combination of which produces the cyclic cystine knot motif. To date, cyclotides have been found in plants from the Rubiaceae, Violaceace and Cucurbitaceae families, and are believed to be part of the host defence system. In addition to their insecticidal effect, cyclotides have also been shown to be cytotoxic, anti-HIV, antimicrobial and haemolytic agents. In this study, we show that the alpine violet Viola biflora (Violaceae) is a rich source of cyclotides. The sequences of 11 cyclotides, vibi A-K, were determined by isolation and MS/MS sequencing of proteins and screening of a cDNA library of V. biflora in parallel. For the cDNA screening, a degenerate primer against a conserved (AAFALPA) motif in the cyclotide precursor ER signal sequence yielded a series of predicted cyclotide sequences that were correlated to those of the isolated proteins. There was an apparent discrepancy between the results of the two strategies as only one of the isolated proteins could be identified as a cDNA clone. Finally, to correlate amino acid sequence to cytotoxic potency, vibi D, E, G and H were analysed using a fluorometric microculture cytotoxicity assay using a lymphoma cell line. The IC(50)-values of the bracelet cyclotides vibi E, G and H ranged between 0.96 and 5.0 microM while the Möbius cyclotide vibi D was not cytotoxic at 30 microM.