2017 Biochemistry - B-Oxidation / Fatty Acid Oxidation Flashcards
What is the function of Acyl-CoA Synthetase on the outer mitochondrial membrane?
Takes free fatty acids (FFA) and converts them to Acyl-CoA for transport across the OUTER membrane only.
What is the function of Carnitine palmitoyl-transferase (CPT-1) in the outer mitochondrial membrane?
Takes Acyl-CoA + Carnitine = acylcarnitine + CoA
ONLY Acylcarnitine can be transported across the INNER membrane to the matrix
What is the function of Carnitine acylcarnitine translocase?
Transports Acylcarnitine to Matrix in exchange for free carnitine from CPT-2.
What is the function of Carnitine palmitoyl-transferase 2 (CPT-2) on the INNER mitochondrial membrane?
It takes the Acylcarnitine from CA-Transferase and converts it to Acyl-CoA and free Carnitine again.
Acyl-CoA can then be used in B-oxidation
How does B-oxidation work? What does it do to Fatty Acyl-CoA molecules.
It takes a fatty acyl-CoA and shortens it by 2 carbons, producing an Acetyl-CoA molecule to be used by the TCA cycle.
Also produces FADH2 & NADH to be used by the Electron Transport Chain.
What is the end-product of ODD numbered Fatty Acyl-CoA molecules?
Produces a Propinyl-CoA (3 carbon) which is converted to succinyl-CoA
What is the major control point of B-oxidation?
Carnitine Palmitoyltransferse 1 (CPT-1)
How is CPT-1 controlled?
Inhibited by Malonyl-CoA
- a product of acetyl-CoA carboxylase
- substrate for fatty acid synthase
An increase in Insulin causes inhibition or stimulation of B-oxidation?
Inhibition
An increase in Glucagon causes inhibition or stimulation of B-oxidation?
Stimulation (un-inhibitied)
Since very long chain FFA can’t cross the mitochondrial membrane where are they processed?
Peroxisomes
Does VLC-FA oxidation in peroxisomes produce energy?
No
Where does oxidation take place for branched FFA? What are products of this oxidation?
Peroxisomes using Alpha and Beta-oxidation
Products:
CO2
Propionyl-CoA
Acetyl-CoA
Where are ketones synthesized? and What enzyme is responsible for this?
Liver mitochondria
HMG-CoA Synthase - isozyme restricted to liver mitochondria
What enzyme is responsible for Ketone use in the muscle and brain cells?
acetoacetate:succinyl-CoA transferase
When does the liver produce ketone bodies? Example physiological states?
When there is an abundance of FFA.
Lipolysis of adipose tissue
Prolonged starvation
Uncontrolled DM Type-1
What are symptoms of Medium-Chain Acyl-CoA Dehydrogenase (MCAD) deficiency? How is it treated?
most common genetic disease of lipid metabolism
non-ketoic hypoglycemia on fasting
fatty infiltrate of liver - leads to liver failure
short chain dicarboxylic acids in urine
Tx: Avoid fasting
What are symptoms of Carnitine deficiency? How is it treated?
Insufficient FFA delivered to mitochondria
non-ketotic hypoglycemia, due to decreased energy for gluconeogenesis
Tx: Oral carnitine
What are symptoms of CPT-1 deficiency? How is it treated?
non-ketotic hypoglycemia, due to decreased B-oxidation
hepatomegaly w/ fatty infiltrate
incerased plasma carnitine
Tx: can be overcome w/ medium-chain FA
What are symptoms of Refsum disease? How is it treated?
deficiency of components needed for peroxisomal oxidation of branched-chain FA
many neurological problems
Tx: reducing phytanic acid from diet (restrain from dairy and meat)
What are symptoms of Jamacian Vomiting Sickness? How is it treated?
Due to eating unripe fruit from Akee tree, contains hypoglycin.
Inhibitor of Acyl-CoA dehydrogenase - stops 1st step of B-oxidation of Fatty Acyl-CoA
