The '''leucines''' are primarily the four isomeric amino acids: leucine, isoleucine, ''tert''-leucine (terleucine, pseudoleucine) and norleucine.<ref>{{Cite journal |last=Zaremska |first=Valeriia |last2=Tan |first2=Jiajun |last3=Lim |first3=Sierin |last4=Knoll |first4=Wolfgang |last5=Pelosi |first5=Paolo |date=2020-07-17 |title=Isoleucine Residues Determine Chiral Discrimination of Odorant‐Binding Protein |url=https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202000872 |journal=Chemistry – A European Journal |language=en |volume=26 |issue=40 |pages=8720–8724 |doi=10.1002/chem.202000872 |issn=0947-6539|url-access=subscription }}</ref> Being compared with the four butanols, they could be classified as butyl-substituted glycines; they represent all four possible variations.
Leucine and isoleucine belong to the proteinogenic amino acids; the others are non-natural.
==Isomers== Including the stereoisomers, six further isomers could be added: <small>D</small>-leucine, <small>D</small>-isoleucine, <small>L</small>-alloisoleucine, <small>D</small>-alloisoleucine, <small>D</small>-''tert''-leucine and <small>D</small>-norleucine.
{| class="wikitable centered" style="margin:1em auto; text-align:center; font-size: 90%" |- | class="hintergrundfarbe6" align="center" colspan="5" | '''Leucines''' |- | class="hintergrundfarbe5" align="left" | Name | <small>L</small>-Leucine || <small>L</small>-Isoleucine || <small>L</small>-''tert''-Leucine (terleucine, pseudoleucine) || <small>L</small>-Norleucine |- | class="hintergrundfarbe5" align="left" | Other names | 2-Amino-4-methylpentanoic acid,<br/>Isobutylglycine | 2-Amino-3-methylpentanoic acid,<br/>''sec''-Butylglycine | 2-Amino-3,3-dimethylbutanoic acid,<br/>''tert''-Butylglycine | 2-Amino-hexanoic acid,<br/>''n''-Butylglycine |- | class="hintergrundfarbe5" align="left" | Structure | 150px || 150px || 110px || 175px |- | class="hintergrundfarbe5" align="left" | CAS-number | 61-90-5 || 73-32-5 || 20859-02-3 || 327-57-1 |- | class="hintergrundfarbe5" align="left" | PubChem | {{PubChem|6106}} || {{PubChem|791}} || {{PubChem|164608}} || {{PubChem|21236}} |- | class="hintergrundfarbe5" align="left" | Molecular formula | colspan="4" | C<sub>6</sub>H<sub>13</sub>NO<sub>2</sub> |- | class="hintergrundfarbe5" align="left" | Molar mass | colspan="4" | 131.18 g/mol |}
==Derivatives== Cycloleucine could be classified as a cyclic derivative of norleucine. With a cyclopentane-ring, it has two hydrogen atoms fewer and thus is not an isomer. The α-carbon atom is not a stereocenter. thumb|none|105px|Cycloleucine
== See also == * L-Photo-Leucine
== Literature == * Jeremy M. Berg, John L. Tymoczko, Lubert Stryer: ''Biochemie.'' 6 Auflage, Spektrum Akademischer Verlag, Heidelberg 2007. {{ISBN|978-3-8274-1800-5}}. * Donald Voet, Judith G. Voet: ''Biochemistry.'' 3. Auflage, John Wiley & Sons, New York 2004. {{ISBN|0-471-19350-X}}. * Bruce Alberts, Alexander Johnson, Peter Walter, Julian Lewis, Martin Raff, Keith Roberts: ''Molecular Biology of the Cell'', 5. Auflage, Taylor & Francis 2007, {{ISBN|978-0815341062}}.
== References == {{Reflist}} Category:Alpha-Amino acids