Lecture 39: Nitrogen fixation-amino acid biosynthesis Flashcards
Amino Acid Biosynthesis
- Plant and microorganisms can make all 20 amino acids
- all others need nitrogen metabolites. In these organisms glutamate is the source of nitrogen via transamination reactions
- Mammals can only synthesize 10 of the amino acids.
- the other 10 are called essential amino acids and must be obtained through the diet
Where do plants and microorganims obtain the 20 amino acids?
they synthesize all 20 amino acids from metabolic precursors that originate in the glycolysis, TCA cycle, or pentose phosphate pathay
Name 5 of the essential amino acids?
Lysine Valine Leucine Isoleucine Methionine
What are some conditional amino acids?
Glutamine Proline Arginine Glycine Cysteine
conditional amino acids
amino acids that synthesis are limited in young, illness, growing animals
Negative Nitrogen Balance
happens when dietary intake of even one essential amino is not enough to meet demand. Thus more protein is broken down than is synthesize and more nitrogen is excreted than is ingested
What does the complexity of an amino acid biosynthetic pathway depends on?
the number of moles of ATP required
Phenylketonuria
PKU
1) results from deficiencies in phenylalanine hydroxylase
2) Important for conversion of phenylalanine
- PKU-Phe accumulates in the blood
- Tyrosine is a building block for neutransmitters, dopamine, noradrenaline, and adrenaline
- Phenylalanin also blocks the transporter that transfers large neutral amino acids into the brain
3) Effects of PKU: mental retardation
4) Treatment: diet
5) PKU is detected by detecting phenylketones in the urine
Roles of Glutathione
- leads to reducing intracellular enviroment
- involved in drug metabolism conjugation to drug for elimination in feces/urine)
Degradation of Amino Acids
- The 20 amino acids are degraded to produce TCA intermediates mostly
- Energy requirements
- 90% from oxidation of carbohydrate and fats
- 10% from oxidation of amino acids - primary physiological purpose of amino acids is to serve as building blocks for protein synthesis
- Amino acids are either glycogenic or ketogenic
Glutogenic Amino Acids
-the amino acids that are converted to precursors for glucose synthesis such as a-ketogluterate, saucily-CoA, fumarate, oxaloacetate, and pyruvate
Ketogenic Amino acids
-the amino acids that are converted to acetyl-CoA or acetoacetate which are precursors for synthesis of fatty acids and ketone bodies
what amino acids are glucogenic due to pyruvate?
- Ala
- Ser
- Cys
- Gly
- Thr
- Trp
What amino acids are glucogenic due to oxaloacetate?
Asp
Asn
What amino acids are glucogenic due to fumarate?
Asp
Phe
Tyr
