Gamma-aminobutyric acid

From Free net encyclopedia

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter found in the nervous systems of widely divergent species.

Gamma-aminobutyric acid
Image:GABA.png
General
Systematic name	4-aminobutanoic acid
Other names	GABA
Molecular formula	C₄H₉NO₂
SMILES	C(CC(=O)O)CN
Molar mass	103.12 g/mol
Appearance	white solid
CAS number	56-12-2
Properties
Density and phase	? g/cm³, ?
Solubility in water	? g/100 ml (? °C)
Melting point	203°C (? K)
Boiling point	? °C (? K)
Acidity (pK_a)	10.43
Basicity (pK_b)	9.77
Chiral rotation [α]_D	?°
Viscosity	? cP at ? °C
Structure
Molecular shape	?
Coordination geometry	?
Crystal structure	?
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	?
NFPA 704
Flash point	? °C
R/S statement	R: ? S: ?
RTECS number	?
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	?
Other cations	?
Related ?	?
Related compounds	?
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

1 Action and receptors
2 Synthesis
3 Pharmacology
4 External links

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Action and receptors

In vertebrates, GABA acts at inhibitory synapses in the central nervous system. GABA acts by binding to specific receptors in the plasma membrane of both pre- and postsynaptic cells. This binding causes the opening of ion channels to allow either the flow of negatively-charged chloride ions into or positively-charged potassium ions out of the cell. This will typically result in a negative change in the transmembrane potential.

In insects, GABA mediates muscle activation at synapses between nerves and muscle cells and also the stimulation of certain glands.

Three general classes of GABA receptor are known. These include GABA_A and GABA_C ionotropic receptors, which are ion channels themselves, and GABA_B metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries (G proteins).

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Synthesis

Organisms synthesize GABA from glutamate using the enzyme L-glutamic acid decarboxylase and pyridoxal phosphate as a cofactor. It is worth noting that this involves converting the principal excitatory neurotransmitter into the principal inhibitory one.

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Pharmacology

Drugs that act as agonists of GABA receptors (known as GABA analogues) or increase the available amount of GABA typically have relaxing, anti-anxiety and anti-convulsive effects.

Drugs that affect GABA receptors: