(R)-Alanine vs (S)-Alanine - Isomer Relationship
What is the relationship between (R)-Alanine and (S)-Alanine?
Mirror images of the simplest chiral amino acid. (S)-Alanine is the natural L-form found in proteins; (R)-Alanine is the unnatural D-form.
| Molecule A | (R)-Alanine (C₃H₇NO₂) |
| Molecule B | (S)-Alanine (C₃H₇NO₂) |
| Relationship Type | enantiomers |
| Difficulty | intermediate |
Introduction
Alanine is one of the 20 standard amino acids. Nature almost exclusively uses one mirror form. Can you tell which is which?
Formula Comparison
Both have the formula C₃H₇NO₂ and the same connectivity: NH₂–CH(CH₃)–COOH. Same formula, same bonds.
Connectivity Analysis
The alpha carbon is bonded to an amino group (–NH₂), a carboxyl group (–COOH), a methyl group (–CH₃), and a hydrogen. Identical connectivity in both molecules.
Spatial Relationship
One molecule is the mirror image of the other. The four different groups around the alpha carbon are arranged in opposite handedness. They cannot be superimposed.
Chirality Check
The alpha carbon has four different substituents: –NH₂, –COOH, –CH₃, and –H. This makes it a chiral center. The R and S labels describe opposite spatial arrangements.
Classification
These are enantiomers — non-superimposable mirror images. In biology, (S)-alanine (L-alanine) is the form used in proteins. The (R)-form (D-alanine) is found in some bacterial cell walls.
Side-by-side 3D comparison with sync rotation, difference highlighting, and guided classification.
Compare (R)-Alanine and (S)-Alanine in 3DRelated Topics
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