Metillanthionina

Metillanthionina, also known as methyl-lanthionine, is a methylated derivative of lanthionine, a sulfur-containing non-proteinogenic amino acid that can form thioether crosslinks in certain peptide natural products. The term appears in some literature dealing with lantibiotics and related biosynthetic peptides, where modified amino acids contribute to the rigid, compact structures of the molecules.

Chemical characteristics and structure

Metillanthionina refers to a lanthionine scaffold bearing one or more methyl substituents. Like lanthionine, it is a crosslinked amino acid containing a thioether linkage, which helps stabilize three-dimensional conformations in peptides. The exact position and nature of the methyl group can vary, yielding potentially multiple isomers described in different studies.

Occurrence and biosynthesis

In nature, lanthionine derivatives arise during the post-translational maturation of certain antimicrobial peptides produced by bacteria (lantibiotics). Methylation of lanthionine residues may occur as part of specialized biosynthetic pathways, either on the amino acid precursor before crosslink formation or on the crosslinked product after assembly. The precise enzymes and steps involved can differ among organisms and peptide families.

Function and relevance

Metillanthionina contributes to the structural diversity and stability of modified peptides. Through methylation, hydrophobicity and steric properties can be altered, potentially influencing peptide folding, target interaction, and biological activity.

Analytical context

Identification of metillanthionina typically relies on mass spectrometry and nuclear magnetic resonance spectroscopy, often in the context of characterizing lantibiotics or related modified peptides. Accurate assignment requires careful interpretation due to isomerism and the complexity of crosslinked, methylated residues.

See also

Lanthionine, lantibiotics, thioether crosslinks.