Metabolism Flashcards
(40 cards)
rate limiting enzyme of glycolysis
phosphofructokinase-1
- inhibited by ATP, citrate
- stimulated by AMP and fruc-2,6-BP
rate limiting enzyme of gluconeogenesis
fructose-1,6-bisphosphatase
- -stimulate by ATP, AcetylCoA
- inhibited by AMP, fruc-2,6-BP
rate limiting enzyme of TCA cycle
isocitrate dehydrogenase
- stimulated by ADP
- inhibited by ATP, NADH
rate limiting enzyme of glycogenesis
glycogen synthase
+ G6P, insulin, cortisol
- epi, glucagon
rate limiting enzyme of glycogenolysis
glycogen phosphorylase
+ epi, glucagon, AMP
- G6P, insulin, ATP
rate limiting enzyme of HMP shunt
G6PD
+ NADP+
- NADPH
rate limiting enzyme of cholesterol synthesis
HMG-CoA reductase
+ insulin, thyroxine
- glucagon, cholesterol
electron transport inhibitors
rotenone, cyanide, antimycin A, CO
– directly inhibit electron transport, causing a decreased proton gradient and block of ATP synthesis
ATP synthase inhibitors
oligomycin
– directly inhibits mitochondrial ATP synthase, causing increased H+ gradient. No ATP is produced because electron transport stops
uncoupling agents
2,4-dinitrophenol, aspirin, thermogenin in brown fat
– increase permeability of mito membrane, causing decreased H+ gradient and increased O2 consumption. electron transport continues without ATP synthesis, produces heat.
Von Gierke Disease (type I)
glycogen storage disease with severe fasting hypoglycemia, increased glycogen in liver, increased blood lactate and hepatomegaly
- G6Phosphatase deficient
- treat with frequent oral glucose/cornstarch, avoid fructose and galactose
Pompe Disease (type II)
glycogen storage disease with cardiomyopathy and systemic findings leading to early death
- lysosomal alpha 1,4 glucosidase (acid maltase) deficient
- Pompe trashes the Pump (heart liver muscle)
Cori disease (type III)
milder form of type I (Von Gierke) glycogen storage disease with normal blood lactate levels
- debranching enzyme (1,6 glucosidase) deficient
- gluconeogenesis is inact
McArdle disease (Type V)
glycogen storage disease with increased glycogen in muscle, but cannot break it down, leading to painful muscle cramps, myoglobinuria after exercise, and arrthythmias 2/2 electrolyte abnormalities
- skeletal muscle glycogen phosphorylase deficiency
- McArdle = Muscle
Fabry disease
- alpha galactosidase A deficiency
- ceramide trihexoside builds up
- X linked inheritance
- peripheral neuropathy, angiokeratomas, CV/renal disease
Gaucher disease
- most common lysosomal storage disease
- glucocerebrosidase deficiency –> glucocerebroside buildup
- hepatosplenomegaly, pancytopenia, aseptic necrosis of the femur, bone crises, Gaucher cells (lipid laden resembling crumpled tissue paper)
- treat with recombinant enzyme
Neimann-Pick Disease
- sphingomyelinase deficiency leads to buildup of sphingomyelin
- progressive neurodegeneration, HSmegaly, cherry red spots on macula, foam cells (lipid-laden macrophages)
- “No man picks his nose with his sphinger (sphingomyelinase)”
Tay-Sachs Disease
- hexosaminidase A deficiency –> buildup of GM2 ganglioside
- progressive neurodegeneration, developmental delay, “cherry-red” spots on macula, lysosomes with onion skin, no HSmegaly
- -Tay SaX (heXosamindase)
Krabbe disease
- galactocerebrosidase deficiency –> buildup of galactocerebroside and psychosine
- peripheral neuropathy, developmental delay, optic atrophy, globoid cells
Metachromatic leukodystrophy
- arylsulfatase A deficiency –> buildup of cerebroside sulfate
- central and peripheral demyelination with ataxia, dementia
Hurler Syndrome
- alpha-L-iduronidase deficiency leading to heparan sulfate and dermatan sulfate buildup
- Dont give Hurler Harry a cookie - developmental delay, gargoylism, Hurler, HSmegaly, airway obstruction, corneal clouding
Hunter syndrome
- XR iduronate sulfase deficiency leading to heparan sulfate and dermatan sulfate buildup
- milder Hurler syndrome +aggressive behavior and NO corneal clouding
- Hunters see clearly (no corneal clouding) and aim for the X (X-linked recessive)
arsenic
inhibits lipoic acid, a cofactor needed for pyruvate dehydrogenase complex
– leads to vomiting, rice-water stools and garlic breath
G6PD deficiency
decreased NADPH in RBCs leads to hemolytic anemia after oxidative stress because NADPH cannot keep glutathione reduced, which in turn cannot detoxify free radicals
- more common in blacks
- Heinz bodies and bite cells seen