The leucines are primarily the four

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

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- ca ...

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 deprot ...

, ''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 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a b ...

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 (carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinogeni ...

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. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino aci ...

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 Cycloleucine is a non-proteinogenic amino acid. It could be classified as a cyclic derivate of norleucine, having two hydrogen atoms less. Leading structure is a cyclopentane-ring. The α-carbon atom is not a stereocenter. Cycloleucine is a non-m ...

could be classified as a cyclic derivative of

. With a

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

-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 Lubert Stryer (born March 2, 1938, in Tianjin, China) is the Emeritus Mrs. George A. Winzer Professor of Cell Biology, at Stanford University School of Medicine. His research over more than four decades has been centered on the interplay of light ...

: ''Biochemie.'' 6 Auflage, Spektrum Akademischer Verlag, Heidelberg 2007. . * Donald Voet, Judith G. Voet: ''Biochemistry.'' 3. Auflage, John Wiley & Sons, New York 2004. . *

Bruce Alberts Bruce Michael Alberts (born April 14, 1938, in Chicago, Illinois) is an American biochemist and the Chancellor’s Leadership Chair in Biochemistry and Biophysics for Science and Education, Emeritus at the University of California, San Francis ...

, Alexander Johnson, Peter Walter, Julian Lewis, Martin Raff, Keith Roberts: ''Molecular Biology of the Cell'', 5. Auflage, Taylor & Francis 2007, {{ISBN, 978-0815341062.

Isomers

Derivatives

See also

Literature