Explore all 20 amino acids: structures, functions, health benefits, and roles in biochemistry. Discover fascinating stories, interactive tools, and in-depth science — for students, researchers, and the curious.

Branched-Chain Amino Acids Three essential amino acids that share a structural quirk, bypass the liver, and burn directly in muscle. Meet leucine, isoleucine, and valine — the BCAAs. Leucine Leu · L · C₆H₁₃NO₂ The most abundant amino acid in muscle protein. Triggers the mTOR switch for protein synthesis. Discovered 1820 from cheese.

Of all the standard amino acids, arginine has the highest side chain pKa — approximately 12.48 — which means its guanidinium group carries a positive charge under virtually all physiological conditions. This isn't true of the other basic amino acids: histidine loses its charge near neutral pH, and lysine, while reliably positive, has a lower pKa than arginine. The guanidinium group of ...

Home› The Chart› Lysine Basic · Positively Charged · Essential Lysine The amino acid that welds collagen fibres together — and the one most commonly missing from plant-based diets, explaining why food combining became a nutrition concept. Symbol Lys · K Discovered

These amino acids participate in lipotropic processes — helping the liver process and export fats rather than allowing them to accumulate. Impaired threonine availability may contribute to conditions associated with hepatic fat deposition.

Explore aspartic acid (Asp) and aspartate transaminase (AST): their properties, metabolic roles, and importance in energy production and amino acid synthesis.

Learn about the amino acid alanine (Ala) and its role in metabolism, including its chemical properties, dietary sources, biological functions, and the importance of alanine transaminase (ALT) in the body.

Glutamine is one of the most commercially produced amino acids, synthesized by bacterial fermentation for use in food science, pharmaceuticals, and cell culture media. Growing cells in a laboratory — for biotechnology, vaccine production, or research — typically requires glutamine-supplemented media because cells in culture consume it rapidly.

The identification was slow, painstaking work, and tryptophan was among the most chemically challenging amino acids to characterize because of its unusual bicyclic indole side chain. Tryptophan's indole ring — a fused benzene and pyrrole — is the most complex side chain of any standard amino acid.

Glutamic acid has a claim few other amino acids can match: it is the most abundant amino acid in nature. In many common proteins, glutamate makes up a substantial share of all amino acid residues.