What does alanine mean?
Alanine is one of the twenty standard amino acids that serve as the building blocks of proteins. It is the smallest chiral amino acid, distinguished by a simple methyl side chain, and is classified as non-essential because the human body can synthesize it rather than requiring it from food. In biochemistry, alanine plays a central role in metabolism: it participates in the glucose–alanine cycle, which shuttles nitrogen and energy between muscle and liver, and its small size makes it a favorite tool for researchers who replace other residues with alanine to test their importance in a protein. Clinically, the enzyme alanine aminotransferase (ALT) is measured in routine blood panels, where elevated levels can signal liver damage. Though strictly a scientific term, alanine is fundamental to understanding how life's molecular machinery is assembled.
nounA non-essential alpha-amino acid that is one of the twenty standard building blocks of proteins, characterized by a simple methyl side chain.
- A naturally occurring alpha-amino acid with the formula CH₃CH(NH₂)COOH, found in nearly all proteins and classified as non-essential because the human body can synthesize it.
"The enzyme's active site is lined with several hydrophobic residues, including alanine."
"Because alanine carries only a small methyl group, it is often used in site-directed mutagenesis to probe which parts of a protein are functionally important."
"Elevated levels of alanine aminotransferase in a blood test can indicate liver damage."
Rarely pluralized except when referring to multiple alanine molecules or multiple alanine residues within a protein sequence.
"The peptide chain contains three alanines in its first ten positions."
Alanine was first made in the lab in 1850 — decades before scientists realized it was already inside every protein in your body.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of alanine
Alanine takes its name from acetaldehyde: it was first synthesized in 1850 by the German chemist Adolph Strecker from acetaldehyde, and the name combines the German 'Al' (from 'Aldehyd') with the '-in(e)' suffix common to amine compounds. The word entered English usage through German chemical literature in the mid-nineteenth century, well before proteins were understood to be built from amino acids. Its naming shares the '-ine' convention with many related compounds such as glycine and valine.
Related word forms
How alanine is actually used
Strictly a technical term used in biochemistry, molecular biology, and medicine; rarely encountered outside scientific contexts. In medical settings it appears most often as part of the enzyme name 'alanine aminotransferase' (ALT), a standard liver-function marker.
Easily confused with alanine
Valine is a different, larger branched-chain amino acid with an isopropyl side chain, whereas alanine has the smallest possible methyl side chain.