Amino acid
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This article is about the class of chemicals. For the structures and properties of the standard proteinogenic amino acids, see Proteinogenic amino acid.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
The generic structure of an alpha amino acid in its unionized form
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
The 21 amino acids found in eukaryotes, grouped according to their side-chains' pKas and charge at physiological pH 7.4
Amino acids ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة] /əˈmiːnoʊ/, /əˈmaɪnoʊ/, or /ˈæmɪnoʊ/) are molecules containing an amine group, a carboxylic acid group, and a side-chain that is specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen. They are particularly important in biochemistry, where the term usually refers to alpha-amino acids.
An alpha-amino acid has the generic formula H2NCHRCOOH, where R is an organic substituent;[1] the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (the α–carbon).
Other types of amino acid exist when the amino group is attached to a
different carbon atom; for example, in gamma-amino acids (such as gamma-amino-butyric acid)
the carbon atom to which the amino group attaches is separated from the
carboxylate group by two other carbon atoms. The various alpha-amino
acids differ in which side-chain (R-group) is attached to their alpha carbon, and can vary in size from just one hydrogen atom in glycine to a large heterocyclic group in tryptophan.
Amino acids serve as the building blocks of proteins,
which are linear chains of amino acids. Amino acids can be linked
together in varying sequences to form a vast variety of proteins.[2]
Twenty amino acids are naturally incorporated into polypeptides and are
called proteinogenic or standard amino acids. These 20 are encoded by
the universal genetic code. Nine standard amino acids are called "essential" for humans because they cannot be created from other compounds by the human body, and so must be taken in as food.
Amino acids are important in nutrition and are commonly used in nutrition supplements, fertilizers, food technology and industry. In industry, applications include the production of biodegradable plastics, drugs, and chiral catalysts.
Contents
[hide]
- 1 History
- 2 General structure
- 2.1 Isomerism
- 2.2 Zwitterions
- 2.3 Isoelectric point
