KETONE METAB Flashcards
Three kinds of ketone bodies
acetoacetate, b-hydroxybutyrate and acetone
Site of Ketogenesis
mitochondrial matrix of the liver
how many molecules of Acetyl CoA is utilized in the first step of Ketone biosynthesis
2 molecules of Acetyl CoA
3rd molecul of Acetyl CoA in ketone biosynthesis is condensed with what and through what enzyme
acetoacetyl CoA via HMG CoA synthase
Where is HMG CoA Synthase only present in?
Mitochondrial matrix of the liver
What is a precursor of Cholesterol and also an intermediate in the catabolism of Leuicine?
HMG CoA?
What is produced when Acetyl CoA is condensed with Acetoacetyl CoA?
HMG CoA
HMG CoA is common to what two pathways?
Ketone Body synthesis and Cholesterol synthesis
What is the rate limiting step of Ketone Biosynthesis?
Formation of HMG CoA from Acetyl CoA
What is the difference between the first two steps of cholesterol and ketone bodies synthesis?
Site. Cholesterol occurs in the cytoplasm while Ketone Biosynthesis occurs in the Mitochondrial Matrix
In what step is the first ketone body produced?
3rd Step: formation of Acetoacetate as HMG CoA is cleaved
What is produced when HMG CoA is cleaved in the third step of Ketogenesis
Acetoacetate, Acetyl CoA
Acetoacetate can be reduced further to produce what Ketone Body?
B-Hydroxybutyrate
Succinyl CoA’s effect on HMG CoA synthase succinylation
inhibits HMG CoA synthase succinylation and decreases rate of ketogenesis
Glucagon’s effect on Ketogenesis
deceases amount of succinyl CoA in mitochondrian, increases ketogenesis
Starvation’s effect on ketogenesis
increase of levels of HMG CoA snythase and its mrRN, increases rate of ketogenesis
Insulin’s effect on Ketogenesis
decreases both activity and mrRna of the enzyme and decreases rate of ketogenesis
Ketone Bodies are metabolized by the mitochondria by what cells?
Extra hepatic cells: brain, skeletal and cardiac
Which two of the ketone bodies can be oxidized to produce energy?
Acetoacetate and b-hydroxybutyrate
In starvation state and diabetes mellitus, what is the effect on glucagon/insulin ratio, acetyl coa and ketogenesis
Increased production of acetyl coa -> increased rate of ketogenesis
compromises LCFA oxidation resulting to hypoglycemia
Lipid accumulation within muscle with weakness
New born has inadequate biosynthesis and renal leakage
Carnitine Deficiency
CPT deficiency in the liver
CPT1
CPT deficiency in the skeletal muscles and liver
CPT 2
Reduced LCFA oxidation, Hypoglycemia and Hypoketosis
Recurrent episodes of myoglobinurias precipitated by prolonged exercise or fasting
CPT Deficiency
Accumulation of Phytanic acid due to a defect in alpha oxidation
Refsum’s disease
caused by eating unripe akee fruit
Jamaican Vomiting Sickness
inactivates medium and short chain acyl CoA dh
Hypoglycin
Absence of peroxisomes
Zellweger’s cerebro hepatorenal syndrome
Medium Chain Acyl DH (MCAD) deficiency
common inborn error of lipid metabolism
autosomal recessive disorder caused by the substitution of a T for an A in position 985 of the MCAD gene
Boxidation of LCFAs proceeds only up to MCFA
