Peptide name : Citropin1.1

Source/Organism : Australian blue mountains tree frog

Linear/Cyclic : Linear

Chirality : L

Peptide length: 16

C-terminal modification: Linear

N-terminal modification : Amidation

Non-natural peptide information: None

Assay type : MTT/MTS assay

Assay time : 6h

Activity : 60% Cytotoxicity at 0.5 µg/ml

Cell line : U-937

Cancer type : Lymphoma cancer

Other activity : Anti-microbial activity

Amino acid composition bar chart :

Molecular mass : 1615.9536 Dalton

Aliphatic index : 1.581

Instability index : 14.1875

Hydrophobicity (GRAVY) : 1.2813

Isoelectric point : 8.5909

Charge (pH 7) : 0.7592

Aromaticity : 0.062

Molar extinction coefficient (cysteine, cystine): (0, 0)

Hydrophobic/hydrophilic ratio : 3

hydrophobic moment : -0.312

Missing amino acid : C,R,W,H,Q,T,P,M,E,Y,N

Most occurring amino acid : G

Most occurring amino acid frequency : 3

Least occurring amino acid : F

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.3, 0.3, 0.5)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)[C@@H](NC(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCCCN)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CC(C)C)NC(=O)CN)C(C)C)[C@@H](C)CC)C(C)C)C(C)C)C(=O)NCC(=O)NCC(=O)N[C@@H](CC(C)C)C(=O)O

1 : Koszałka P, et al. Antitumor activity of antimicrobial peptides against U937 histiocytic cell line. Acta Biochim Pol. 2011; 58:111-7.

2 : Wabnitz PA, et al. The citropin peptides from the skin glands of the Australian Blue Mountains tree frog Litoria citropa. Part 2: sequence determination using electrospray mass spectrometry. Rapid Commun Mass Spectrom. 1999; 13:1724-32. doi: 10.1002/(SICI)1097-0231(19990915)13:17<1724::AID-RCM706>3.0.CO;2-T

Paper title : Antitumor activity of antimicrobial peptides against U937 histiocytic cell line.

Doi : https://doi.org/Not available

Abstract : We investigated cytotoxic activity of antimicrobial peptides of different origin (both naturally occurring and synthetic), structure and known mechanisms of action against human histiocytic lymphoma cell line U937. The strongest cytotoxic activity against U937 cell line was shown by Pexiganan MSI-78, followed by Citropin 1.1, Protegrin 1 and a synthetic lipopeptide, N-α-palmitoyl-L-lysyl-L-lysine amide (Pal-Lys-Lys-NH₂). The cytotoxic activity of the peptides was more dependent on the time of incubation than concentration. Only for the lipopeptide, whose mode of action was restricted to disruption of electric potential of the cell membrane, the correlation between cytotoxicity and concentration was almost linear. The high cytotoxicity of Pexiganan MSI-78, Protegrin 1 and the lipopeptide could be basically explained by their membranolytic activity leading to necrosis. However, in the case of Citropin 1.1, the cell membrane integrity was disrupted only slightly and independently of the peptide concentration. Therefore, some other mechanism of action might be responsible for its strong dose-dependent cytotoxic activity, e.g., membranolytic activity leading to apoptosis. Furthermore, TNF-α production due to LPS (lipopolysaccharide) stimulation was suppressed by the presence of Citropin 1.1, Pexiganan MSI-78 or Protegrin 1, but not by Buforin 2 or the lipopeptide. Our experiments have shown that cytotoxic activity is not limited to some specific molecular structure of a peptide, but rather to the length of the peptide chain as it is likely to affect the efficiency of the tumor cell membrane disruption and interaction with LPS.

Paper title : The citropin peptides from the skin glands of the Australian Blue Mountains tree frog Litoria citropa. Part 2: sequence determination using electrospray mass spectrometry.

Doi : https://doi.org/10.1002/(SICI)1097-0231(19990915)13:17<1724::AID-RCM706>3.0.CO;2-T

Abstract : A combination of electrospray mass spectrometry, Lys-C digest/mass spectrometry and automated Edman sequencing provides the amino acid sequences of nineteen citropin peptides isolated from the granular dorsal and submental glands of the Blue Mountains tree frog Litoria citropa. Citropin 1.1 [Gly Leu Phe Asp Val Ile Lys Lys Val Ala Ser Val Ile Gly Gly Leu (NH(2))] and citropin 1.2 [Gly Leu Phe Asp Ile Ile Lys Lys Val Ala Ser Val Val Gly Gly Leu (NH(2))] are the two major skin peptides: both show significant wide-spectrum antibacterial activity.