First Aid BioChem Flashcards
What is a kinase?
Uses ATP to add high-energy phosphate group onto substrate.
What is the function of Vitamin B1 (thiamine)?
In thiamine pyrophosphate (TTP), a cofactor for several dehydrogenase enzyme reactions: Pyruvate dehydrogenase (links glycolysis to TCA); alpha-ketoglutarate dehydrogenase (TCA cycle); Transketolase (HMP shunt); Branched-chained keno acid dehydrogenase.
**dry beri beri, wet beri beri, and WK syndrome.
What is a phosphorylase?
Adds inorganic phosphate onto substrate without using ATP.
What is a phosphatase?
Removes phosphate group from substrate (e.g. Fructose-1,6-bisphosphate).
What does dehydrogenase do?
Catalyzes oxidation-reduction reactions (e.g. Pyruvate dehydrogenase).
What does a hydroxylase do?
Adds hydroxyl group (-OH) on to substrate.
What does a carboxylase do?
Transfers CO2 groups with the help of biotin (Pyruvate carboxylase).
What does mutase do?
It relocates a functional group within a molecule (e.g. Vitamin B12-dependent methylmalonyl-CoA mutase).
What do Rotenone, cyanide, antimycin A, and CO do?
They are electron transport inhibitors- they directly inhibit electron transport, causing a decreased proton gradient and block ATP synthesis.
What does Oligomycin do?
ATP synthase inhibitors- Directly inhibit mitochondrial ATP synthase, causing an increased proton gradient. No ATP is produced because electron transport stops.
What is the mechanism of action of 2,4-Dinitrophenol (used for weight loss)?
Uncoupling agents- increase the permeability of a membrane, causing a decreased proton gradient and O2 consumption. ATP synthesis stops but electron transport continues. Produces heat.
What occurs when you have a N-acetyl glutamate deficiency?
It is a required cofactor for carbamoyl phosphate synthetase I. Absence of N-acetylglutamate leads to hyperammonemia. It’s presentation is similar to carbamoyl phosphate synthetase I deficiency, however, increased ornithine with normal urea cycle enzymes suggests hereditary N-acetylglutamate deficiency.
What is cystinuria?
AR-Hereditary defect of renal PCT and intestinal amino acid transporter for Cysteine, Ornithine, Lysine, and Arginine. Excess cystine in the urine can lead to precipitation of hexagonal cystine stones. Tx- urinary alkalinization (potassium citrate, acetazolamide), to decrease cystine stones.
What is maple syrup urine disease?
AR-Blocked degradation of branched AA (Isoleucine, Leucine, Valine) due to decreased alpha-ketoacid dehydrogenase (B1). Causes severe CNS defects, intellectual disability, and death.
Glycogen Storage Disease (type I)?
Von Gierke Disease (AR) - Deficient enzyme: Glucose-6-phosphatase (autosomal recessive)
Severe fasting hypoglycemia, increased glycogen in the liver, increased blood lactate, hepatomegaly
Glycogen Storage Disease (type II)?
Pompe Disease (AR)- Deficient enzyme: lysosomal alpha-1,4-glucosidase (acid maltase) Cardiomyopathy and systemic findings leading to early death.
Glycogen Storage Disease (type III):
Cori disease (AR)- deficient enzyme: debranching enzyme (alpha-1,6-glucosidase). Milder form of type I with normal blood lactate levels.
Glycogen Storage Disease (type V):
McArdle disease (AR) - deficient enzyme: skeletal muscle glycogen phosphorylase (myophosphorylase) Increase glycogen in muscle, but cannot break it down, leading to painful muscle cramps, myoglobinuria (red urine) with strenuous exercise and arrhythmia from electrolyte abnormalities.
What is Fabry disease?
Lysosomal Storage Disease:
Deficiency of alpha-galactosidase A.
Accumulated substrate: ceramide trihexoside
–>Peripheral neuropathy of hands/feet, angiokeratomas, cardiovascular/renal disease.
