Peptide name : LL-37(17-32)(C-terminal fragment of LL-37; Human, mammals, animals)

Source/Organism : Human

Linear/Cyclic : Cyclic

Chirality : L

Peptide length: 16

C-terminal modification: Cyclic

N-terminal modification : Amidation

Non-natural peptide information: None

Assay type : MTT assay

Assay time : 2 h

Activity : LC50 : 30 ± 0 μM

Cell line : KBv

Cancer type : Tumor

Other activity : Anti-bacterial activity

Amino acid composition bar chart :

Molecular mass : 2045.4762 Dalton

Aliphatic index : 1.337

Instability index : 24.7812

Hydrophobicity (GRAVY) : -0.075

Isoelectric point : 11.723

Charge (pH 7) : 3.7592

Aromaticity : 0.125

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

Hydrophobic/hydrophilic ratio : 1

hydrophobic moment : 2.4472

Missing amino acid : C,W,H,T,P,M,E,S,Y,A,G

Most occurring amino acid : R

Most occurring amino acid frequency : 3

Least occurring amino acid : Q

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.2, 0.1, 0.5)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCCCN)NC(=O)[C@@H](N)Cc1ccccc1)[C@@H](C)CC)C(C)C)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CC(=O)O)C(=O)N[C@@H](Cc1ccccc1)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H](CC(N)=O)C(=O)N[C@@H](CC(C)C)C(=O)N[C@H](C(=O)O)C(C)C

1 : Li X, et al. Solution structures of human LL-37 fragments and NMR-based identification of a minimal membrane-targeting antimicrobial and anticancer region. J Am Chem Soc. 2006; 128:5776-85. doi: 10.1021/ja0584875

Paper title : Solution structures of human LL-37 fragments and NMR-based identification of a minimal membrane-targeting antimicrobial and anticancer region.

Doi : https://doi.org/10.1021/ja0584875

Abstract : To understand the structure and activity relationship of human LL-37, a series of peptide fragments was designed. The N-terminal fragment, LL-37(1-12), was not active, while the C-terminal fragment, LL-37(13-37), killed Escherichia coli, as well as drug-sensitive and drug-resistant cancer cells. A 13-residue core antibacterial and anticancer peptide, corresponding to residues 17-29 of LL-37, was identified based on total correlated spectroscopy by trimming nonessential regions (TOCSY-trim). Because LL-37 acts on bacterial membranes, three-dimensional structures of its fragments were determined in micelles by NMR, including structural refinement by natural abundance 15N and 13C chemical shifts. Aromatic-aromatic interactions in the N-terminal fragment were proposed to be essential for LL-37 aggregation. The LL-37 core peptide adopts a similar structure in the micelles of SDS or dioctanoyl phosphatidylglycerol. This structure is retained in the C-terminal fragment LL-37(13-37) and very likely in intact LL-37 based on peptide-aided signal assignments. The higher antibacterial activity of the LL-37 core peptide than aurein 1.2 was attributed to additional cationic residues. To achieve selective membrane targeting, D-amino acids were incorporated into LL-37(17-32). While the D-peptide showed similar antibacterial activity to the L-diastereomer, it lost toxicity to human cells. Structural analysis revealed hydrophobic defects in the new amphipathic structure of the D-peptide, leading to a much shorter retention time on a reversed-phase HPLC column. It is proposed that hydrophobic defects as a result of incoherent hydrophobic packing provide a structural basis for the improvement in cell selectivity of the LL-37 fragment.