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Amino Acids - general description
Amino acids - small biological molecules formed polypeptide chains in peptides and proteins. Chemically amino acid contains three main groups connected to the central Cα atom (alpha carbon): amino group (-NH2), carboxylic acid group (-COOH) and side chain group (-R), that is why amino acids sometimes are referred as an alpha-amino acids. Central Cα atom is chiral. Generally, in all living organisms only L-amino acids are present. All amino acids are differ only by the side chain. In living organisms only 20 amino acids are naturally presents. Some organisms can synthesize all amino acids, but many organisms can synthesize only few of them (non-essential amino acids), and other amino acids (essential amino acids) only obtained from digestion process.
Amino acid structure
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The schematic al representation of amino acid. In this diagram the chiral properties of the central alpha-carbon are not shown. This type of diagram usually used in most of the representations, because if it is not specially stated, all amino acids are considered as L-amino acids. |
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Schematic diagram of the structure of L-amino acid. The chirality of alpha-carbon atom is clearly shown. In many diagrams these chiral properties are not represented in order to simplify the picture. |
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