Peptide name : Protegrin 1

Source/Organism : Alpha helical peptide without cysteines

Linear/Cyclic : Linear

Chirality : L

Peptide length: 18

C-terminal modification: Linear

N-terminal modification : Amidation

Non-natural peptide information: None

Assay type : MTT/MTS assay

Assay time : 6h

Activity : 61% 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 : 2160.6216 Dalton

Aliphatic index : 0.538

Instability index : 62.1333

Hydrophobicity (GRAVY) : -0.25

Isoelectric point : 10.663

Charge (pH 7) : 5.7194

Aromaticity : 0.111

Molar extinction coefficient (cysteine, cystine): (1490, 1740)

Hydrophobic/hydrophilic ratio : 1.57142857

hydrophobic moment : 0.2202

Missing amino acid : W,H,Q,T,P,M,I,E,K,S,D,N,A

Most occurring amino acid : R

Most occurring amino acid frequency : 6

Least occurring amino acid : L

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.0, 0.1, 0.2)

SMILES Notation: CC(C)C[C@H](NC(=O)[C@H](CCCNC(=N)N)NC(=O)CNC(=O)CNC(=O)[C@@H](N)CCCNC(=N)N)C(=O)N[C@@H](CS)C(=O)N[C@@H](Cc1ccc(O)cc1)C(=O)N[C@@H](CS)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](Cc1ccccc1)C(=O)N[C@@H](CS)C(=O)N[C@H](C(=O)N[C@@H](CS)C(=O)N[C@H](C(=O)NCC(=O)N[C@@H](CCCNC(=N)N)C(=O)O)C(C)C)C(C)C

1 : Kokryakov VN, et al. Protegrins: leukocyte antimicrobial peptides that combine features of corticostatic defensins and tachyplesins. FEBS Lett. 1993; 327:231-6. doi: 10.1016/0014-5793(93)80175-t

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

Paper title : Protegrins: leukocyte antimicrobial peptides that combine features of corticostatic defensins and tachyplesins.

Doi : https://doi.org/10.1016/0014-5793(93)80175-t

Abstract : Porcine leukocytes contained three homologous peptides, PG-1, 2 and 3, that manifested potent microbicidal activity against Escherichia coli, Listeria monocytogenes and Candida albicans in vitro. The peptides ('protegrins') were composed of 16 (PG-2) or 18 amino acid residues, and, like tachyplesins (broad-spectrum antibiotic peptides of horseshoe crab hemocytes), they contained two intramolecular cystine disulfide bonds. Considerably smaller than defensins, protegrins nevertheless showed substantial homology to them, especially to the 'corticostatic' rabbit defensin, NP-3a. The relatively simple structure of protegrins should provide useful prototypes for constructing congeners with selectively enhanced host defense activities.

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.