Biosynthesis of Amino Acids

How is alanine synthesized?

• It’s synthesized by transamination of pyruvate and glutamate

• it requires PLP

• How is asparagine synthesized? Describe the steps

• Synthesized by transamination of aspartame.

• 1. oxaloacetate becomes aspartate

• 2. aspartate becomes asparagine using ATP and glutamine

• Enzyme: asaparagine synthetase

• enzyme has an ammonia tunnel (CPS2) that moves ammonia from one active site to another

How is aspartate made?

Asparagine is deaminated by asparginase by hydrolysis to make aspartate

Can also be made by transamination oxaloacetate and glutamate

What are the conditionally essential amino acids acids?

arginine, cysteine, glutamine, glycine, proline, tyrosine

What is required to make creatine?

Arginine, glycine, and methionine (SAM)

How is creatine present in the muscles?

It’s phosphorylation to phosphocreatine, which allows storage of a phosphate group for quick energy

What does high levels of creatinine mean?

Can be a sign of renal damage

How is tyrosine made? What is the enzyme?

-Enzyme: Phenylalanine hydroxylase

-enzyme is tetrahydrobiopterin (B4) dependent

-hydroxylates at C4 of phenyl group of phenylalanine

What’s the importance of S-adenosylmethionine?

-Methylating agent for 300 metabolites

-involved in synthesis of homocysteine, creatine, and epinephrine

What is required to form SAM/complete the Methionine Cycle?

-5-methyltetrahydrafolate (B12)

-ATP

-Methionine

What is glutathione derived from?

-Glutamate, cysteine, and glycine

-It’s a reducing agent (disulfide bonds are reduced

Neurotransmitters: Glutamate

Main excitatory neurotransmitter

Neurotransmitters: Aspartate

Excitatory neurotransmitter

Neurotransmitters: D-serine

co-agonist of N-methyl D-aspartate (NMDA) type glutamate receptors.

Neurotransmitters: Glycine

inhibitory neurotransmitter within spinal cord, brainstem, and retina.

Neurotransmitters: Describe catecholamine and its pathway. What is required?

• Fight or flight response

• Released in response to emotional or

physical stress

• Synthesized in brain, nerve tissues, or

adrenal glands

NEED: tyrosine and methyl transferase

Neurotransmitters: GABA Describe its function and pathway

• vitamin B6-dependent

reaction (PLP dependent)

-made from glutamate

• Inhibitor neurotransmitter for CNS

• Reduces neuronal

excitability.

NEED: PLP and Glutamate

Neurotransmitters: Serotonin Describe its function and pathway

Derived from tryptophan

• Key role in functions such as mood,

sleep, digestion, blood clotting and

sexual desire.

Describe the methionine cycle