Tyrocidine is a family of eight cationic cyclic decapeptides produced by Bacillus brevis, a soil microorganism. Tyrocidine was first reported by Dubos in 1941 and was the first commercially available antibiotic, but it was found to have toxicity towards human blood cells and reproductive cells. Tyrocidine can be composed of 4 different amino acid sequences, giving Tyrocide A-D. Tyrocidine is the major component, which also contains gramicidin. Tyrocidine exhibits broad-spectrum activity against Gram-positive and Gram-negative bacteria and is the major component of the Tyrothricin complex.
Tyrocidines A, B, and C are cyclic decapeptides. The biosynthesis of tyrocidine involves three enzymes. Parts of its sequence are identical to gramicidin S. In fact, Tyrothricin was later found ot be a mixture of the peptides gramicidin and tyrocidine.
| Mechanism of Action |
The mechanism of action of tyrocidines is not fully understood; however, they are known to act by disturbing lipid bilayers of the bacterial cell membrane. The exact affinity and location of tyrocidine within the phospholipid bilayer is not yet known. |
| Molecular Formula | C66H87N13O13 (for Tyrocidine A) |
| References |
Dubos RJ (1939) Studies on a bacterial agent extracted from a soil bacillus. J. Exp. Med. 70:11 PMID 19870884 Fong J and Krueger AP (1950) The lytic action of Tyrothricin and its derivatives on Staphylococcus aureus. J. Gen. Physiol. 133:311 Gordon AH et al (1943) The amino-acid composition of Tyrocidine. Biochem. J. 37:313 |