Leucine

(CC) Image: David E. Volk
Leucine, one of the twenty common amino acids.

Leucine, abbreviated as Leu or L, is one of the twenty common amino acids used by living organisms to build proteins. It is one of the non-polar, aliphatic, hydrophobic amino acids. In proteins, leucine is usually buried in a hydrophobic pocket within the protein structure sequestered away from the protein surface. Leucine is similar to the amino acids isoleucine and valine in both structure and function.