General Information

    • DRAMP ID

    • DRAMP00877

    • Peptide Name

    • Circulin-A (CIRA; Plant defensin)

    • Source

    • Chassalia parviflora

    • Family

    • Belongs to the cyclotide family

    • Gene

    • Not found

    • Sequence

    • GIPCGESCVWIPCISAALGCSCKNKVCYRN

    • Sequence Length

    • 30

    • Evidence code

    • Protein level

Activity Information

    • Biological Activity

    • Antibacterial, Antifungal, Antiviral, Anti-Gram+, Anti-Gram-, Antimicrobial

    • Target Organism

      • Gram-positive bacterium: Staphylococcus aureus (MIC=0.19 µM).
      • Gram-negative bacterium: Proteus vulgaris (MIC=54.6 µM).
      • Fungi: Candida kefyr (MIC=18.6 µM) and Candida tropicalis (MIC=19.4 µM).
      • NOTE: Medium with 10 mM phosphate buffer.

    • Hemolytic Activity

      • [Ref.10430870] EC50 = 1020 μM against blood type A human erythrocytes (1.8 × 10^8 cells/ml). Note: EC50 is the peptide concentrations causing 50% hemolysis.

    • Cytotoxicity

    • No cytotoxicity information found in the reference(s) presented

    • Binding Target

    • Not found

Structure Information

    • Linear/Cyclic

    • Cyclic

    • N-terminal Modification

    • No specific N-terminal

    • C-terminal Modification

    • No specific C-terminal

    • Other Modifications and Unusual Amino Acids

    • Disulfide bonds between Cys1 and Cys17; Cys5 and Cys19; Cys10 and Cys24.

    • Stereochemistry

    • L

    • Structure

    • Alpha helix (1 helices; 4 residues)

    • Structure Description

    • The molecule is stabilised by three disulfide bonds, two of which form an embedded loop completed by the backbone fragments connecting the cysteine residues. A third disulfide bond threads through the centre of this loop to form a "cystine-knot" motif. This motif is present in a range of other biologically active proteins, including omega-contoxin GVIA and Cucurbita maxima trypsin inhibitor.

    • PDB ID

    • 1BH4 resolved by NMR.
    • DRAMP00877 helical wheel diagram
    • 1BH4-> 

Physicochemical Information

    • Formula

    • C134H216N38O39S6

    • Absent Amino Acids

    • DFHMQT

    • Common Amino Acids

    • C

    • Mass

    • 3693.25

    • PI

    • 8.11

    • Basic Residues

    • 3

    • Acidic Residues

    • 1

    • Hydrophobic Residues

    • 9

    • Boman Index

    • -12.24

    • Hydrophobicity

    • 0.417

    • Aliphatic Index

    • 78

    • Half Life

      • Mammalian:30 hour
      • Yeast:>20 hour
      • E.coli:>10 hour

    • Extinction Coefficient Cystines

    • 7365

    • Absorbance 280nm

    • 253.97

    • Polar Residues

    • 15

DRAMP00877

DRAMP00877 chydropathy plot

Comments Information

    • Function

    • Probably participates in a plant defense mechanism. Has antibiotic activity. Inhibits the cytopathic effects and replication of the human immunodeficiency virus. Relatively ineffective against Gram-negative bacteria such as E. coli and P. aeruginosa.

    • PTM

    • This is a cyclic peptide which contains three disulfide bonds 1-17; 5-19; 10-24.

Literature Information

  • ·Literature 1

    • Title

    • An unusual structural motif of antimicrobial peptides containing end-to-end macrocycle and cystine-knot disulfides.

    • Reference

    • Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):8913-8918.

    • Author

    • Tam JP, Lu YA, Yang JL, Chiu KW.
  • ·Literature 2

    • Title

    • Solution structure by NMR of circulin A: a macrocyclic knotted peptide having anti-HIV activity.

    • Reference

    • J. Mol. Biol. 1999; 285:333-345.

    • Author

    • Daly NL, Koltay A, Gustafson KR, Boyd MR, Casas-Finet JR, Craik DJ.