Amino Acid Anabolism Flashcards
List the 10 NONessential amino acids
Ala, Asp, Asn, *Cys, Glu, *Gln, Gly, Pro, Ser, *Tyr
List the 10 essential amino acids
PVT TIM HALL
Phe, Val, Trp, Thr, Ile, Met, His, *Arg, Leu, Lys
Conditionally essential amino acid: This amino acid is essential for neonates because this pathway is not well developed in newborns
Cysteine
Conditionally essential amino acid: This amino acid is essential for PKU patients; require Phe (essential)
Tyrosine
Conditionally essential amino acid: This amino acid is required for growing infants and under severe illness
Glutamine
Conditionally Essential amino acid: This amino acid is generally considered essential even though it is generated in the urea cycle.
Arginine
Describe the synthesis of Glutamate
alpha-ketoglutarate to Glutamate via Glutamate dehydrogenase, transaminases, etc.
Describe the synthesis of Glutamine
Glutamate–>Glutamine via Glutamine synthesis
Describe the synthesis of Alanine
pyruvate–>Alanine via ALT (Alanine transaminase)
Describe the synthesis of Aspartate
OAA–>Asp via AST (Aspartate transaminase)
Describe the synthesis of Asparagine
Aspartate–>Asparagine via Asparagine synthetase
Describe the synthesis of Tyrosine
Phenylalanine–>Tyrosine via phenylalanine hydroxylase
Describe the synthesis of Proline
Glutamate–>Prline via a 3 step pathway (later described)
Describe the synthesis of Serine
3-P-glycerate–>Serine via a 3 step pathway (later described)
Describe the synthesis of Glycine
Serine–>Glycine via H4 folate in 1-carbon pool
Describe the synthesis of Cysteine
Serine–>Cysteine using Methionine as sulfur source
1st step of making either Proline or Ornithine from Glutamate
Glutamate–>Glutamate semialdehyde using “uncharacterized enzymes”; ATP–>ADP = Pi, NADH–>NAD+
Two fates of Glutamate Semialdehyde
1) Glutamate semialdehyde–>Ornithine via aminotransferase. Ornithine is an intermediate in the urea cycle and can potentially make Arginine.
2) Glutamate semialdehyde–>pyrroline carboxylate (spontaneous rxn)–>Proline via Pyyroline-5-carboxylase reductase
How do we get Glutamate from glucose?
When we break down Proline (made from Glutamate), glutamate goes back into alpha-KG and alpha-KG comes from the TCA cycle=GLUCOSE!
1st step of Serine synthesis
3-Phosphoglycerate–> 3-Phosphopyruvate via phosphoglycerate dehydrogenase; NAD+–>NADH + H+
2nd step of Serine synthesis
3-Phosphopyruvate–>3-Phosphoserine via aminotransferase; glutamate–>alpha-KG; OH replaced by a phosphate
3rd step of Serine synthesis
3-Phosphoserine–>Serine via phosphatase; use a water, lose a Pi
Name an essential component of the one carbon pool of metabolism
Tetrahydrofolate
What happens to Serine in the presence of tetrahydrofolate and enzymes?
Take off the CH2OH and replace it with just a hydrogen=Glycine
How is Glycine made from Serine?
Serine in the presence of H4folate uses a water and becomes Glycine.
What is the difference between Serine and Cysteine?
The sulfur attached to the end of Cysteine
Describe the steps involved in the normal breakdown of Methionine AND the synthesis of Cysteine from Serine with sulfur from Methionine
Mammals eat Methionine as an essential amino acid. In the presence of ATP, Methionine–>S-adenosylmethionione (sulfur attached to adenosine) via methionine adenosyltransferase. You can detach the methyl group from AdoMet making S-adenosylhomocysteine. Split that out and release adenosine to go back to make ATP. We have methionine minus a methyl group= Homocysteine. We bring in Serine from somewhere else and link it to homocysteine and transfer the sulfur group to make Cystathionine. Using an enzyme, take off the NH3 and you have Cysteine and alpha-Ketobutyrate.
Which amino acid is needed to make purines and pyrimidines?
Glutamine. It donates nitrogens to nucleotdies.
Carbon source for Alanine
Pyruvate (from glucose)
Carbon source for Aspartate
OAA (from glucose)
Carbon source for Glutamate
alpha-KG (from glucose)
Carbon source for Serine
3-P-Glycerate (from glucose)
For the nonessential amino acids, all but one can be made in mammals starting with glucose. Which one cannot?
Tyrosine
How is the bioactive amine Histamine produced?
Decarboxylation of Histidine. Histamine causes dilation of blood vessels, bronchoconstriction, and secretion of HCl
How is the bioactive amine Nitric Oxide (NO) produced?
From arginine by nitric oxide synthase. NO relaxes vascular and intestinal smooth muscles. Acts via cGMP.
What bioactive amine acts as neurotransmitters?
Peptides
Describe the synthesis of Creatinine
Arg, Gly, and Met can be made into Creatine which can be converted into Creatine-Phosphate using creatine kinases and ATP–>ADP. Spontaneously, Creatine-P can turn into Creatinine which is then filtered into the urine.
What is measured in the blood clinically to estimate renal function?
Creatinine
The bioactive amines Serotonin (AKA 5-HT) and Melatonin are derived from what?
Tryptophan
Bioactive amine: describe the synthesis of Thyroxin
Thyroid hormones are produced by the iodinatin of tyrosine resides of thyroglobulin.
Name two other Tyrosine products
Melanin (Tyrosinase deficiency results in albinism in chow chows) and it’s a precursor to the quinone of CoQ. Thyroid deficiency can come from iodine deficiency.
Bioactive amines: describe the synthesis of catecholamines
Neurotransmitters: Catecholamines include dopamine, norepinephrine, and epinephrine. They are all derived from Tyrosine (Methionine as methyl donor for epinephrine)
How to recognize Dopamine, Norepinephrine, and Epinephrine molecules
They all the Tyrosine ring
Which amino acid is a major stimulatory neurotransmitter in the CNS? And also a precursor for gamma-Aminobutyrate
Glutamate; GABA is a major inhibitory transmitter in the brain and synthesied via glutamate decarboxylase.
Which amino acid is primarily found in inhibitory interneurons in the spinal cord, where it blocks impulses traveling down the cord in motor neurons to stimulate skeletal muscle?
Glycine (also participates in 1-carbon pool)
What causes major problems (dilated cardiomyopathy, retinopathy, renal dz, fat emulsification/absorption, reproductive failure, and immune deficiency) in deficient cats?
Taurine
What amino acid synthesizes taurine?
Cysteine
