Amino Acids: Difference between revisions

See [http://en.wikipedia.org/wiki/Glycine Glycine] in Wikipedia, where the structure is shown. Glycine is the smallest amino acid, since its side-chain is nothing  but a single hydrogen. Glycine is frequently found in '''turns''', since the steric clashes of larger amino acids would be problematic. Turns typically occur on the surfaces of proteins, between [[Secondary structure|beta-strands or alpha-helices]]. It is common to find '''[[Conservation, Evolutionary|highly conserved]] glycines in turns on protein surfaces''', since mutation to a bulkier residue would interfere with the fold. Glycine also occurs in  [[Secondary structure|beta-strands and alpha-helices]], although its frequency in alpha helices is low (second lowest, after proline, p. 125 in <ref name="kesselbental">Kessel, Amit, and Nir Ben-Tal. ''Introduction to Proteins: Structure, Function, and Motion''. CRC Press, 2011. 653 pages.</ref>). Glycine is commonly found at the C-terminus of alpha helices, and is considered a ''helix terminator'' (p. 125 in <ref name="kesselbental" />).