Bio 11 - HMP Shunt And Other Sugars Flashcards
What is the enzyme G6PD used for?
It turns glucose-6-phosphate into Ribulose-5-P + 2 NADPH. The Ribulose-5-P is then used for PRPP, which is essential for nucleotide synthesis (ribose back bone).
What enzyme turns oxygen into an oxygen radical inside the lysosome so it can destroy what ever it consumed?
NADPH oxidase.
What enzyme turns the oxygen radical into peroxide?
Superoxide dismutase.
What enzyme turns hydrogen peroxide into hypochlorus acid (HOCl-)?
Myeloperoxidase.
Which immunodeficiency disease has a deficiency of NADPH oxidase?
Chronic granulomatous disease; they are susceptible to infection by catalase-positive organisms.
What are substances that tend to oxidize RBCs?
Anti-malarial drugs (Primaquine and chloroquine). Nitrofurantoin. Dapsone. Sulfonamides. Isoniazid. Naphthalene. Fava beans. Probably Ibuprofen and High-dose ASA.
What do we see in patients with glucose-6-phosphate dehydrogenase deficiency?
Hemolytic anemia. Heinz bodies (clumps of oxidized hemoglobin inside RBCs) and Bite cells (when the spleen took a bite to remove the oxidized hemoglobin in RBCs).
What is the most common enzyme deficiency that causes disease in humans?
Glucose-6-Phosphate Dehydrogenase Deficiency. It is an X-linked disorder.
What is the cause of Essential fructosuria?
Deficiency of Fructokinase (which converts fructose into fructose-1-phosphate).
What are the symptoms of Essential Fructosuria?
Fructose is spills into the urine. Nothing happens other than that.
What is the cause of Fructose intolerance?
Deficiency in the enzyme Aldolase B (which converts fructose-1-P into DHAP or Glyceraldehyde).
What are the symptoms of Fructose intolerance?
Hypoglycemia. Vomiting. Hepatomegaly. Jaundice.
What are the symptoms of Galactokinase deficiency?
Causes an accumulation of Galactitol in blood, urine. This can lead to infantile cataracts
What is the cause of Classic galactosemia? What are the symptoms?
Caused by a deficiency of Gal-1-P uridyltransferase. Causes cataracts, hepatomegaly, jaundice, failure to thrive, intellectual disability.
What are the symptoms of lactose deficiency?
Lactose pases into the colon where bacteria start to consume it and go nuts. They make a lot of gas, the lactose also draws water into colon osmotically, making osmotic diarrhea.
What is the rate-limiting step of the pentose phosphate pathway?
G6PD.
Which tissues of the body use the pentose phosphate pathway?
RBCs. Liver. Adrenal cortex. Mammary glands (during lactation).
Explain why a deficiency of the enzyme that is the rate-limiter for the HMP shunt can result in hemolytic anemia.
The enzyme G6PD is responsible for generating NADPH, which is used to produce reduced glutathione, an important antioxidants. Without G6PD, RBCs are more susceptible to oxidative damage, which leads to hemolysis.
What does deficiency of the enzyme Galactokinase cause?
Galactokinase deficiency.
What does deficiency of the enzyme Aldose B cause?
Fructose intolerance.
What does deficiency of the enzyme Lactase cause?
Lactose intolerance.
What does deficiency of the enzyme Galatctose-1-phosphate uridyltransferase cause?
Galactosemia.
What does deficiency of the enzyme Fructokinase cause?
Essential fructosuria.
Why is NADPH important?
Synthesizing fatty acids and cholesterol. Generate O2 free radicals. Protect RBCs from O2 free radicals. Cytochrome P450 enzymes.
