Glycine

Glycine is the simplest amino acid, with a hydrogen atom as its side chain. Its small size lets it fit into protein structures that restrict larger amino acids.

Amino acid: An organic molecule containing amino and carboxyl groups; amino acids are the building blocks of proteins. Glycine is the smallest member of this molecular family.
Ramachandran plot: A graph of the backbone dihedral angles phi and psi allowed in a protein structure. Glycine occupies a wider region of this plot because its side chain is only hydrogen.
Glycine cleavage system: A mitochondrial enzyme system that breaks glycine down while transferring a one-carbon unit to tetrahydrofolate. This pathway is a major route for glycine catabolism in animals.
Henri Braconnot: A French chemist who isolated glycine from gelatin in 1820. Braconnot first obtained glycine by treating gelatin with sulfuric acid.
Zwitterion: A molecule bearing both positive and negative formal charges while remaining electrically neutral overall. In water near neutral pH, glycine predominantly carries this paired-charge form.
Protein backbone: The repeating sequence of nitrogen, alpha-carbon, and carbonyl atoms forming a polypeptide chain. Glycine’s minimal side chain leaves this structural framework unusually unconstrained.
Serine hydroxymethyltransferase: An enzyme that reversibly converts serine and tetrahydrofolate into glycine and 5,10-methylenetetrahydrofolate. It links glycine metabolism to serine and one-carbon chemistry.
Gelatin: A mixture of proteins derived from collagen, used in foods, pharmaceuticals, and laboratory work. Its acid hydrolysis yielded the sweet-tasting substance Braconnot named gelatin sugar.
Chirality: The property of an object or molecule being distinguishable from its mirror image. Glycine lacks a chiral center, unlike nearly all other protein-building amino acids.
Alpha helix: A common protein secondary structure in which a polypeptide chain coils into a right-handed helix. Glycine can destabilize helices because its flexibility makes the ordered shape costly.

Linked from 23 pages