Catabolism Of Carbon Skeleton Flashcards
Which two amino acids give you ketone bodies?
Leucine and lysine
Conversion of the remaining amino acid carbon skeleton can give you what 3 things?
Energy (TCA cycle intermediates), glucose in liver, or ketone bodies
What TCA intermediates can catabolism of carbon skeleton give you (4)
Alpha ketoglutarate, succinyl CoA, fumarate, or oxaloacetate
Arginine
- Essential or nonessential
- Cleaved to produce
- Eventually converted to?
~not that important
- Nonessential
- Ornithine
- Alpha ketoglutarate
FIGLU reacts with?
FIGLU is in which amino acid reaction?
FIGLU test tells you what?
Folic acid (needed for nucleotide synthesis)
Degradation of Histidine into alpha ketoglutarate
If there is a folic acid deficiency (leads to neural tube defects-spina bifida)
~so you can use histidine to detect folic acid deficiency
What amino acid forms pyruvate?
Alanine (transamination) - also cystine can
What amino acid forms succinyl CoA
Methionine
What should you think of when you hear 1 carbon metabolism?
SAM: S-adenosyl methionine
What does SAM do?
Two examples of what SAM products are
What does SAM require
Transfers its methyl group to acceptor molecules (makes methylated products)
Epinephrine, melatonin, and creatine
Vitamin B12
5 aminoacidopathies?
Homocystinuria, maple syrup urine disease, hyperphenylalaninemias, alkaptonuria, albinism
Homocysteine metabolism
- Requires what 2 things?
- Why is homocysteine important?
- How do you lower homocysteine levels?
- Vitamin B12 and PLP
- Increased levels can lead to MI or stroke in someone in their 20s (atherosclerosis)
- By eating greens
Things increased homocysteine cause:
- Nitric oxide dysfunction which causes
- Irritated blood vessels which causes
- Endothelial injury which causes
- Increased oxidative damage which causes
- Vasoconstriction
- Inflammation
- Clot formation
- Atherosclerosis
Besides MI/stroke, what else can homocysteine cause in young people
Alzheimer’s and rheumatoid arthritis and neural tube defects
Homocystinuria
- What enzyme is deficient
- High plasma/urinary levels of __ and low levels of __
- Symptoms
- Treatment
- Cystathionine synthetase
- High levels of homocysteine and methionine and low levels of cysteine
- Mental retardation, osteoporosis, ectopia lentis (dislocation of lens)
- Diet low in methionine and supplementation of B6, B12, and folate
Maple syrup urine disease:
- Reduced activity of what enzyme
- Elevated plasma and urinary levels of what three amino acids
- Symptoms are seen?
- Symptoms?
- Branched chain alpha keto acid dehydrogenase
- Leucine, isoleucine, and valine (and their alpha keto acids)
- 2-3 weeks after birth
- Sugary urine smell, infant difficult to feed, extensive brain damage occurs in surviving children (usually die after a year tho)
Phenylalanine metabolism:
- Pheylalanine gets converted to which amino acid?
- By which enzyme?
- Tyrosine
2. Phenylalanine hydroxylase
Which of the following is an essential amino acid: phenylalanine or tyrosine?
Phenylalanine
Tyrosine is nonessential only in the presence of the adequate dietary phenylalanine
Deficiency of phenylalanine hydroxylase will cause what disorder?
PKU (phenylketonuria) / Type 1 hyperphenylalaninemia
Other types of hyperphenylalaninemia can be caused by a deficiency in which enzymes?
Biopterin (BH2) reductase / biopterin (BH2) synthase
PKU
- High levels of what in tissues/plasma/urine
- Low levels of?
- Feature of urine? Why?
- Phenylalanine
- Tyrosine
- Mousy/musty odor due to elevated levels of phenylacetate, phenylactate, and phenylpyruvate (path that creates these 3 normally does not happen, but it will due to abnormal accumulation of phenylalanine)
Symptoms of PKU
What test diagnoses PKU? When is this test done?
Mental retardation, seizures, psychoses, hypopigmentation
Guthrie test - done after 2-3 days of milk feeding
Why would PKU lead to hypopigmentation?
Because if you have PKU, phenylalanine is not being converted to tyrosine and tyrosine is the precursor for melanin
Treatment for PKU
Decrease amount of phenylalanine in diet (not absence since its essential); tyrosine must be supplied in the diet
Tyrosinemia type I
- Accumulation of?
- Deficiency in what enzyme?
- Urine symptom?
- Treatment?
- Fumaryl acetoacetate and its metabolites
- Fumaryl acetoacetate hydrolase (last enzyme in tyrosine metabolism)
- Cabbage like odor
- Dietary restriction of phenylalanine and tyrosine
Alkaptonuria
- Enzyme deficiency?
- At what age does it show symptoms
- Urine symptom?
- What can it cause
- Homogentisate oxidase
- 40
- Colored (darkened)
- Large joint arthritis
What is onchronosis?
What causes it?
Pigmentation of cartilage and connective tissues
Oxidation of homogentisate (Alkapton bodies)
Tyrosine is precursor for
Neurotransmitters (dopamine, epinephrine, NE)
What does dopamine help do
Deficient dopamine will cause
Chemical messenger that control muscle movement
Parkinsons
Albinism is caused by deficient ?
Symptoms
Tyrosinase (so decreased production of melanin)
Complete absence of pigment, vision defects, photophobia
Tyrosine also gives rise to what hormone?
Thyroid hormone
