The leucines are primarily the four

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

leucine Leucine (symbol Leu or L) is an essential amino acid that is used in the biosynthesis of proteins. Leucine is an α-amino acid, meaning it contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α-Car ...

isoleucine Isoleucine (symbol Ile or I) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the depro ...

, ''tert''-leucine ( terleucine, pseudoleucine) and

norleucine Norleucine (abbreviated as Nle) is an amino acid with the formula CH3(CH2)3CH(NH2)CO2H. A systematic name for this compound is 2-aminohexanoic acid. The compound is an isomer of the more common amino acid leucine. Like most other α-amino acids, ...

. Being compared with the four

butanol Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 OH, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a bu ...

s, they could be classified as butyl-substituted

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (G ...

s; they represent all four possible variations. Leucine and isoleucine belong to the

proteinogenic amino acid Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation from RNA. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) ...

s; the others are non-natural.

Isomers

Including the stereoisomers, six further isomers could be added: D-leucine, D-isoleucine, L-alloisoleucine, D-alloisoleucine, D-''tert''-leucine and D-norleucine.

Derivatives

Cycloleucine could be classified as a cyclic derivative of

. With a

cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic compound, alicyclic hydrocarbon with chemical formula C5H10, C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and ...

-ring, it has two hydrogen atoms fewer and thus is not an isomer. The α-carbon atom is not a stereocenter.

Literature

* Jeremy M. Berg, John L. Tymoczko, Lubert Stryer: ''Biochemie.'' 6 Auflage, Spektrum Akademischer Verlag, Heidelberg 2007. . * Donald Voet, Judith G. Voet: ''Biochemistry.'' 3. Auflage, John Wiley & Sons, New York 2004. . * Bruce Alberts, Alexander Johnson, Peter Walter, Julian Lewis, Martin Raff, Keith Roberts: ''Molecular Biology of the Cell'', 5. Auflage, Taylor & Francis 2007, .

References

{{Reflist Alpha-Amino acids

Isomers

Derivatives

See also

Literature

References