crotamine and Hemolysis

Complicated and mystifying as the snake envenomation process may appear, the toxic principles of snake venoms are biochemical entities that could be isolated, purified and characterized. In this review, the toxicological process of envenomation and the biochemical basis of venom toxicity are presented for those not directly involved in venom research but who nevertheless have an interest in snake venom poisoning.

Topics: Animals; Anticoagulants; Blood Coagulation; Crotalid Venoms; Heart; Hemolysis; Neurons; Neurotoxins; Proteins; Snake Venoms

Crotamine, a myotoxin from the venom of South American rattlesnake, is structurally related to β-defensins, antimicrobial peptides (AMPs) found in vertebrate animals. Here, we tested the antibacterial properties of crotamine and found that it killed several strains of Escherichia coli, with the MICs ranging from 25 to 100 μg ml⁻¹. Time-kill and bacterial membrane permeabilization assays revealed that killing of bacteria by crotamine occurred within 1 h and reached the maximum by 2 h. Additionally, the anti-E. coli activity of crotamine was completely abolished with 12.5 mM NaCl. Furthermore, the three intramolecular disulfide bonds of crotamine appeared dispensable for its antibacterial activity. The reduced form of crotamine was active against E. coli as well. However, crotamine showed no or weak activity up to 200 μg ml⁻¹ against other species of Gram-negative and Gram-positive bacteria. Crotamine showed no appreciable hemolytic activity to erythrocytes. Our studies revealed that crotamine is also an AMP that kills bacteria through membrane permeabilization. However, crotamine appears to have a narrow antibacterial spectrum, distinct from many classical β-defensins, reinforcing the notion that crotamine originated from the β-defensin gene lineage, but has undergone significant functional diversification.

Topics: Animals; Anti-Bacterial Agents; Crotalid Venoms; Crotalus; Erythrocytes; Escherichia coli; Gram-Negative Bacteria; Gram-Positive Bacteria; Hemolysis; Membranes; Mice; Microbial Sensitivity Tests; Permeability; Time Factors