gamma-Aminobutyric acid: a novel tetragonal phase

Area of Science:

• Crystallography
• Neuroscience
• Biochemistry

Background:

• Gamma-aminobutyric acid (GABA) is a key inhibitory neurotransmitter.
• Previous studies characterized the monoclinic phase of GABA, revealing a partially folded zwitterionic form with a gauche conformation.
• Understanding different crystalline phases of GABA is crucial for its biological function.

Purpose of the Study:

• To characterize the crystal structure of gamma-aminobutyric acid (GABA) in its tetragonal phase.
• To compare the molecular conformation and hydrogen bonding patterns with the previously known monoclinic phase.
• To investigate potential implications for GABA's neurotransmission activity.

Main Methods:

• Single-crystal X-ray diffraction analysis was performed on the tetragonal phase of GABA.
• Molecular conformation and intramolecular distances were analyzed.
• Hydrogen bonding networks were identified and characterized.

Main Results:

• In the tetragonal phase, GABA molecules adopt a partially folded zwitterionic form with a trans conformation around the C2-C3 bond.
• A fourth, weaker hydrogen bond forming a two-center bifurcated bond was observed.
• Evidence suggests a potential intramolecular bridging hydrogen bond, different from the monoclinic phase.

Conclusions:

• The tetragonal phase of GABA exhibits a distinct molecular conformation and hydrogen bonding pattern compared to the monoclinic phase.
• Altered intramolecular N...O distances in the tetragonal phase may impact GABA's neurotransmission.
• The findings provide new insights into the structural polymorphism of GABA and its biological relevance.