Alpha-amino-isobutyric Acid

2-Aminoisobutyric acid (also known as α-aminoisobutyric acid, AIB, α-methylalanine, or 2-methylalanine) is the non-proteinogenic amino acid with the structural formula H₂N-C(CH₃)₂-COOH. It is rare in nature, having been only found in meteorites, and some antibiotics of fungal origin, such as alamethicin and some lantibiotics.

Synthesis

In the laboratory, 2-aminoisobutyric acid may be prepared from acetone cyanohydrin, by reaction with ammonia followed by hydrolysis.
Industrial scale synthesis can be achieved by the selective hydroamination of methacrylic acid.

Biological activity

2-Aminoisobutyric acid is not one of the proteinogenic amino acids and is rather rare in nature (''cf.'' non-proteinogenic amino acids). It is a strong helix inducer in peptides due to Thorpe–Ingold effect of its gem-di methyl group. Oligomers of AIB form 3₁₀ helices.

Ribosomal incorporation into peptides

2-Aminoisobutyric acid is compatible with ribosomal elongation of peptide synthesis. Katoh ''et al.'' used flexizymes and an engineered a tRNA body to enhance the affinity of aminoacylated AIB-tRNA species to elongation factor P. The result was an increased incorporation of AIB into peptides in a cell free translation system. Iqbal ''et al.''. used an alternative approach of creating an editing deficient valine—tRNA ligase to synthesize aminoacylated AIB-tRNA^Val. The aminoacylated tRNA was subsequently used in a cell-free translation system to yield AIB-containing peptides.

References

{{DEFAULTSORT:Aminoisobutyric acid, 2-
Branched-chain amino acids
Amino acids
Non-proteinogenic amino acids