Brazil, Peru, Bolivia, Paraguay, Uruguay, Argentina*
Classification
Myoneurotoxin, cell-penetrating peptide, antimicrobial peptide, and defensin-like peptide
Molecular weight
4726,63 daltons
Isoelectric point
pI 9.54, highly positive
Length
Polypeptide of 42 amino acids
Primary sequence
KQCHKKGGHCFPKEKICLPPSSDFGKMDCRWRWKCCKKGSG
Isoform
Crotamine-Ile 19 (isoleucine substitution at position 19)*
Chemical formula
C346H530N90O82S8 (isoform 1)*
Solubility
Highly soluble in water and physiological solutions
Stability
Highly stable in solution, relative large pH range, and temperature
Folding
Crotamine is arranged in a topology stabilized by 3 disulfide bridges: an -helix with residues 1–7 and a two-stranded antiparallel -sheets with residues 9–13 and 34–38.
Disulfide bonds
C4–C36; C11–C30; C18–C37
Physiological and neurological activity
Hind limb paralysis in mice in final concentration 2.5 mg of toxin/kg body mass Necrosis of muscle cells
Electrophysiology activity
Mammalian Kv1.1, Kv1.2, and Kv1.3 blocker with IC(50) of nM
Cytosol, vesicles, nucleus, centrioles, and chromosomes
Mechanism of DNA-crotamine interaction
Only electrostatic: crotamine (+charged)—DNA (−charged) aggregate
Uptake
Within 5 minutes, and permanence in the cells for approximately 24 hours
Mechanism of penetration
Membrane heparan sulfate proteoglycans binding and clathrin-dependent endocytosis
Cell penetrating activity (in vivo)
Selective: dividing (actively proliferating cells), for example stem cells in bone marrow, spleen, liver, lung, and so force.
Localization in brain
Able to cross blood-brain barrier, and localization in brain cells
Molecular carrier
Intracellular delivery of DNA (both circular and linear molecules) in vivo and in vitro. Final complex size dependent delivery.
Antimicrobial activity
Modest against Gram-positive and Gram-negative bacteria, with some exceptions, for example Micrococcus luteus, and with no detectable activity against the filamentous fungus Aspergillus fumigatus and Trichophyton rubrum at concentrations up to 125 g/mL.
Antimycotic (-fungal) activity
Significant activity against yeast Candida spp.
Cancer cells toxicity
Toxic (concentration ranged from 0.1 to 10 M) Inoffensive for normal cells
Anticancer activity (in vitro)
Strong against melanoma cells in vitro
Anticancer activity (in vivo)
Inhibition and delay of melanoma growth in vivo in mouse model
Marker of centrioles and cell cycle; marker of actively proliferating normal cells; biomolecules carrier; tool for cancer cells investigation; marker of cancer cells in vitro and in vivo, and as antifungal and anticancer agent. Prototype for new drug design.
Several old data about crotamine need to be revised using modern approaches.