Alamethicin is a peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

 antibiotic

Antibiotic

An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

, produced by the fungus Trichoderma viride

Trichoderma viride

Trichoderma viride is a fungus and a biofungicide.It is used for seed and soil treatment for suppression of various diseases caused by fungal pathogens. It is also a pathogen in its own right, causing green mould rot of onion.-Biology:...

. It contains the non-proteinogenic amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 2-aminoisobutyric acid

2-Aminoisobutyric acid

2-Aminoisobutyric acid, or α-aminoisobutyric acid or α-methylalanine or 2-methylalanine, is an amino acid with the structural formula is H2N-C2-COOH. It is contained in some antibiotics of fungal origin, e.g. alamethicin and some lantibiotics. It is not one of the proteinogenic amino acids and...

 (Aib), which strongly induces helical

Helix

A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...

 peptide structures. The peptide sequence is:

Ac-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phl

(Ac = acetyl, Phl = phenylalaninol)

In cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

s, it forms voltage

Voltage

Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

-dependent ion

Ion

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 channels by aggregation of four to six molecules.

Further reading

• LR Jones, SW Maddock and HR Besch Jr. Unmasking effect of alamethicin on the (Na+,K+)-ATPase, beta-adrenergic receptor-coupled adenylate cyclase, and cAMP-dependent protein kinase activities of cardiac sarcolemmal vesicles. J. Biol. Chem., Vol. 255, Issue 20, 9971-9980, Oct, 1980.
• Explore the crystal structure at the protein data bank: http://www.rcsb.org/pdb/explore/explore.do?pdbId=1AMT
  • From "A voltage-gated ion channel model inferred from the crystal structure of alamethicin at 1.5-A resolution."