Biochemistry: Protein Structure, Dynamics, and Enzyme Kinetics Vocabulary Flashcards

Amino Acid Structure, Properties, and Classification

• General Structure of Amino Acids

  • An amino acid is an organic compound containing both an amino group ($\text{--NH}_2$) and a carboxyl group ($\text{--COOH}$) attached to a central carbon atom called the $\alpha$-carbon.

  • The $\alpha$-carbon is also bonded to a hydrogen atom ($\text{--H}$) and a variable side chain ($\text{--R}$) that confers unique chemical properties to each amino acid.

• Stereochemistry and Configuration

  • All $\alpha$-amino acids derived from proteins, except Glycine, possess at least one asymmetric center (the $\alpha$-carbon), making them chiral stereocenters with optical activity.

  • Biological amino acids exist almost exclusively in the L-configuration, named by structural analogy to L-glyceraldehyde.

*   Key structural exceptions among standard amino acids:
    *   **Glycine:** Achiral ($\text{--R} = \text{--H}$) due to two hydrogen atoms on the $\alpha$-carbon.
    *   **Proline:** Contains a secondary $$\alpha$null