, General Structural characteristic of Amino Acids
All the 20 amino acids found in proteins have a carboxyl (COOH)
group and an amino (-NH2) group bound to the same carbon atom
called the α carbon
, Amino acids differ from each other in their side chains
or R-groups, attached to the α-carbon
The 20 amino acids of proteins are often referred to as
the standard or primary or normal amino acids.
One of the 20 amino acids, proline is an imino (-NH)
(secondary amino group) acid not an amino (-NH2)
acid as are other 19.
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