醫學系一醫學系一 AAB9902011B9902011 朱庭儀朱庭儀B9902030B9902030 林靖容林靖容

GABA-GABA-γ-γ-Aminobutyric Acid, Aminobutyric Acid, Glutamate, and GlycineGlutamate, and Glycine

Glutamate

• In neuroscience, glutamate plays a key role in long-term potentiation, learning and memory.

• Glutamate is the precursor for the synthesis of GABA, the lack of which may lead to stiff-man syndrome.

• Metabolism

§ R1-amino acid + R2-α-ketoacid ⇌R1-α-ketoacid + R2-amino acid

§ glutamate + H2O + NADP+ →

α-ketoglutarate + NADPH + NH3 + H+

Functional uses

Functional usesFunctional uses

• Neurotransmitter

§ Nerve impulses→release of glutamate from the pre-synaptic cell→glutamate receptors in the opposing post-synaptic cell bind with glutamate→ activated.

§ Excitotoxicity due to glutamate is associated with certain diseases.

• Flavor enhancer ： MSG=monosodium glutamate

• Nutrient

• Plant growth： Auxigro

• NMR Spectroscopy： alignment medium.

Functional usesFunctional uses

Glycine

• Biosynthetic intermediate

• Neurotransmitter§ Glycine is an inhibitory neurotransmitter in

the central nervous system. Activation of glycine receptors are can cause an Inhibitory postsynaptic potential (IPSP).

NMDA receptor

• Functional roleIt is the predominant molecular device for controlling synaptic plasticity and memory function.

• Clinical significanceRecently, NMDARs were associated with a rare autoimmune disease

GABA-γ-Aminobutyric acid

• The chief inhibitory neurotransmitter in the mammalian central nervous system

• Neurons that produce GABA as their output are called GABAergic neurons,like Medium Spiny Cells

GABAA –a ligand-gated ion channel

• Composed of two subunits• When binding to the GABAB receptor activates

the trimeric G protein • Inhibit voltage-gated Ca++ channels or activate K+ channels.

GABAB-a G protein-coupled receptor

Structure and conformation

• GABA is found mostly as a zwitterion• gas:highly folded solid: more extended solution: five different conformations

synthesis

GABA’s applications

• Increase production of α waves, reduce β wave, Controls θ waves, • Also involved in the production of endorphins• Stimulate the production of Human Growth

Hormone

Comparison

Amino acids Function class Secretion sites

GABA Inhibitory CNS; invertebrate neuromuscular junction

Glutamate Excitatory CNS; invertebrate neuromuscular junction

Glycine Inhibitory CNS