All amino acids share a common core structure comprised of an amino group, a carboxyl group, and a hydrogen atom, all bonded to a central alpha (α) carbon.
Common Structural Components of Amino Acids Explained
Every amino acid, the building blocks of proteins, has a similar foundational structure. These common structural components are essential for the formation of peptide bonds and the overall structure of proteins.
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Alpha (α) Carbon: This is the central carbon atom to which all other components are bonded. It acts as the backbone's point of attachment for the amino group, carboxyl group, hydrogen atom, and the distinguishing R-group.
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Amino Group (-NH₂ or -NH₃⁺): This group consists of a nitrogen atom bonded to two hydrogen atoms. At physiological pH, the amino group is usually protonated, carrying a positive charge (-NH₃⁺).
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Carboxyl Group (-COOH or -COO⁻): This group consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (-OH). At physiological pH, the carboxyl group is usually deprotonated, carrying a negative charge (-COO⁻).
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Hydrogen Atom (H): A single hydrogen atom is also bonded to the alpha carbon.
These shared elements provide the basic architecture, while the "R-group" or "side chain," which varies between different amino acids, provides each amino acid with its unique chemical properties.
In summary, while the R-group distinguishes each of the 20 common amino acids, they all share a central α-carbon bonded to an amino group, a carboxyl group, and a hydrogen atom.
