Alanine
Alanine — A non-essential alpha-amino acid (Ala, A) with a methyl side chain. One of the simplest and most abundant amino acids in proteins.
What Is Alanine?
Alanine (Ala, A) is the simplest chiral amino acid with a methyl side chain (MW: 89.09 Da). It has the highest intrinsic alpha-helix propensity after leucine and serves as the reference residue in the alanine scanning technique, the most fundamental SAR method in peptide research.
Alanine Scanning
Each residue in the peptide is individually replaced with alanine, and the effect on biological activity is measured. Positions where Ala substitution eliminates activity identify critical pharmacophoric residues. Positions tolerating Ala substitution are candidates for stability-enhancing modifications. This systematic approach was pioneered by Cunningham and Wells in 1989.
Additional Roles
- D-Ala substitution: D-Ala at position 2 of enkephalins was among the first demonstrations of protease resistance through stereochemical inversion
- Aib (alpha-aminoisobutyric acid): The alpha-methylated analog of alanine, used in ipamorelin to constrain backbone geometry
Frequently Asked Questions
What is Alanine?
A non-essential alpha-amino acid (Ala, A) with a methyl side chain. One of the simplest and most abundant amino acids in proteins.
Why is Alanine important in peptide research?
Alanine is a fundamental concept in amino acid as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.