Flashcards in Metabolism Deck (44)
What is fomepizole
Antidote for alcohol poisoning
It inhibits alcohol dehydrogenase
What is disulfiram
Inhibits acetaldehyde dehydrogenase causing acetylaldehyde to accumulate making the patient feel hungover.
What does alcohol metabolism depend on?
Depends mostly on NAD + being converted to NADH
rate determening enzyme for glycolysis
Fructose - 1,6 bisphosphatase
Rate limiting enzyme for gluconeofenesis
TCA cycle rate limiting enzyme
Glycogenesis Rate limiting enzyme
Glucose 6 phosphate dehydrogenase
HMP Shunt RLE
Important for NADPH formation
Carbamoyl phosphate synthetase II
De novo pyrimidine synthesis RLE
Glutamine-phosphoribosylpyrophosphate amidotransferase (PRPP)
De nobo purine synthesis RLE
Carbamoyl phosphate synthetase I
Urea cycle RLE
Fatty acid synthesis RLE
Carnitine acyltransferase I
Fatty acid oxidation RLE
Cholesterol synthesis RLE
First enzyme in the TCA?
Citrate synthase takes Acetyl-CoA to make isocitrate.
Outside sourcs of odd chain fatty acids, branched chain amino acids, and methionine can enter the TCa through what form?
the urea cycle can input into the TCA through which form?
Through fumarate formation.
At the expense of also creating urea.
what enzyme is specifically inhibited by Arsenic?
Lipoic acid resulting in vomiting, rice water stools, and garlic breath.
Patient is unable to link glycolysis and TCA cycle through mitochondria.
what molecule does the TCA utilize in its formation of products?
Utilizes Acetyl-Coa to create NADH, FADH, CO2 and GTP`
What is the starting substrate of the TCA?
Ends as oxaloacetate.
which steps of the TCA create NADH?
Isocitrate from citate
Succinyl coa from isocitrate
Oxaloacetate from malate
Which part of the TCA results in FADH2 formation?
Succinate to fumarate
Which part of the TCA results in GTP formation?
Succinyl CoA to succinate reaction.
what does the HMP shunt do?
Excess glucose -6- p can be funneled into this pathway to promote NADPH creation.
Also gives ribose for nucleotide synthesis.
What role does glucose 6 phosphate dehydrogenase deficiency entail?
NADPH is necessary to keep glutathione reduced which in turn detoxifies free radicals and peroxides.
Decreased NADPH in RBC's leads to hemolytic anemia. Fava beans and sulfonamides can really ramp this up.
Look for heinz bodies (denatured hemoglobin) and bite cells
Deficiency in aldolase B
Fructose - 1 - phosphate accumulates causing a deficiency in phosphate.
Look for flare ups after drinking juice and presence of fructose in the urine.
What is required for fatty acid synthesis?
Citrate transport from the mitochondria to the cytosol.
Mostly in the liver and lactating mamary glands/ fat tissue.
What is required for for long chain fatty acid degradation?
Requires carnitine dependent transport into the mitochondral matrix
What happens in a carnitine deficiency?
Inherited defect in transport of long chain fatty acids into the mitochondra.
Toxic accumulation leading to weakness, hypotonia, and hypoketoic hypoglycemia.
How are ketone bodies created?
In the liver, fatty acids and amino acids are metabolized to acetoacetate and beta hydroxybutyrate.
In prolonged starvation, and diabetic ketoacidosis, oxaloacetate is depleted for gluconeogenesis.
How man calories in...
carbs and protein have 4 kcals
fat has 9kcal
1g alcohol has 7kcal
How is cholesterol synthesized?
Cholesterol needed to maintain cell membrane integrity and to synthesize bile acid, steroids and vitamin D.
Rate limiting enzyme is HMG-CoA
What does HMG-CoA do?
Insulin acts on it to convert HMG-CoA to mevalonate. this occurs in the synthesis of cholesterol.
statins actively inhibit this bad boy
Hormone sensitive lipase
Degradation of triglyerides stored in adipocytes
Hepatic triglyceride lipase
degradation of triglycerides remaining in IDL
What does lipoprotein lipase do?
LPL degrades TGs corculating in chylomicrons and VLDLs and is found on vascular endothelial cell surfaces.
What does LCAT do?
Esterfies cholestero to be carried in HDL
What is the purpose of apo protein B-48 and B100?
B48 mediates chylomicron secretion
B-100 binds the LDL receptor at the liver.
Which lipoproteins carry the most cholesterol?
Lipoproteins LDL and HDL
Thus excessive chylomicrons, TG and cholesterol floating in blood.
Causes pancreatitis and hepatosplenomegaly
Increased LDL and cholesterol
Defected LDL receptors
Causes accelerated atherosclerosis