Gramicidin B

Gramicidin B

Gramicidin B is a natural antibiotic produced by the bacteria Bacillus brevis. It is a member of the gramicidin family, which also includes Gramicidin A and Gramicidin C. These antibiotics are known for their ability to form ion channels in cell membranes, disrupting the normal function of the cell and leading to its death.

Structure

Gramicidin B is a linear peptide composed of 15 amino acids. Its structure is characterized by the presence of unusual amino acids, such as D-amino acids and ornithine, which are not commonly found in proteins. The sequence of amino acids in gramicidin B is N-Formyl-L-Val-Gly-L-Ala-D-Leu-L-Ala-D-Val-L-Val-D-Val-L-Trp-D-Leu-L-Trp-D-Leu-L-Trp-D-Leu-L-Trp-COOH.

Mechanism of Action

The mechanism of action of gramicidin B involves the formation of ion channels in the cell membrane. These channels allow for the uncontrolled flow of ions across the membrane, disrupting the electrochemical gradient that is essential for the cell's survival. This leads to a loss of membrane potential, which in turn leads to cell death.

Clinical Use

Gramicidin B, like other members of the gramicidin family, is used primarily as a topical antibiotic. It is often combined with other antibiotics, such as neomycin and polymyxin B, in over-the-counter ointments for the treatment of minor skin infections.

Safety and Toxicity

While gramicidin B is generally safe for topical use, it can cause skin irritation in some individuals. It is not used systemically due to its high toxicity to human cells. The formation of ion channels in human cell membranes can disrupt normal cell function and lead to cell death.

See Also

• Gramicidin
• Gramicidin A
• Gramicidin C
• Bacillus brevis
• Antibiotics

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