beta oxidation of fatty acids
trans fatty acid
hydrogens on opposite side of chain; formed in industrial hydrogenation of fish and plant oils; it improves thermal and oxidation stability
fatty acids are stored as what?
enzyme that cuts fatty acids
where does beta oxidation occur?
oxidation/burning of fatty acids in the mitochondrial matrix
what activate the lipases?
how is fatty acids circulate in blood?
they are bound to serum albumin
major serum protein; make up 60% of total plasma protein; binds free fatty acids, steroid hormones and bilirubin
how can longer chain of FA enter the matrix?
they are converted to acylcarnitine derivatives by carnitine:acylcarnitine translocase
transport long chain fatty acids across inner membrane of mitochondria
fatty acids in the body are always bound to what 3 things?
CoA or glycogen or carnitine:acylcarnitine translocase
how many membranes do fatty acids cross to get inside the mitochondria?
3 membranes: plasma membrane, outer mitochondrial membrane, inner mitochondrial membrane
how does carnitine:acylcarnitine translocase (CAT) work?
it sends carnitine out and acylcarnitine in; this is done to recycle the concentration of carnitine on the outside of the mitochrondrial membrane so it can bind to fatty acids and be transported into the inner mitochondrial membrane
what is the cofactor for fatty acids breakdown?
what is the cofactor for fatty acids synthesis?
how many carbons does the beta-oxidation pathway degrade from fatty acids at a time?
3 main stages of beta-oxidation pathway
activation of fatty acids in the cytosol; transport into mitochondria; degradation to 2 carbon fragments in the mitochondrial matrix in the 4 steps repeated as a spiral
4 key repeated reactions in b-oxidation
oxidation; hydration; oxidation; thiolysis
each round of reaction generates one molecule each of what?
QH2, NADH, acetyl CoA, fatty acyl CoA that is 2 carbons shorter each round
how many acetyl CoA, QH2, NADH is produced when a 16-carbon fat is burned?
8 acetyl CoA, 7 QH2, 7 NADH
how many ATPs is produced when a 16-carbon fat is burned?
what are 2 exceptions when fatty acids can be made into glucose?
odd number of carbons on a fatty acid (because any 3-carbon molecule can be converted to pyruvate) and glycerol
very long chain fatty acids are oxidized first where?
last cleavage of odd-chain length fatty acids give you what?
acetyl CoA and propionyl CoA (a 3-carbon molecule)
peroxisomes break down fatty acids in order to do what?
detoxify and make hydrogen peroxide (H2O2) to destroy bacteria
what happens if some one has carnitine deficiency?
hypoglycemia, reduced carnitine in tissues and impaired long chain fatty acids metabolism
MCAD (medium chain acylCoA dehydrogenase) defect
show intermittent hypoglycemia, onset in 2nd year of life, dicarboxylic aciduria extensive during attacks but undetectable when healthy
what is the primary fuel during fasting?
where is ketone bodies produced?
where is ketone bodies converted back to acetyl CoA?
muscle and tissues
ketone bodies are sources of energy for what during fasting?
brain, heart, skeletal muscles
ketone bodies synthesis occurs only where?
what are ketone bodies?
fatty acid derivatives that are easy to transport in blood without albumin or other fatty acid binding proteins
what is the preferred energy source for kidney cortex cells and cardiac muscle?
acetoacetate and beta-hydroxybutyrate
what is the ratio of acetoacetate:b-hydroxybutyrate?
1:1; these are readily interchangable
how does hyperclycemia causes dehydration?
reduces excretion of ketone bodies in urine, this causes increase in plasma [H+] and leads to ketoacidosis
how does diabetes mellitus leads to excess ketone bodies adn ultimately ketoacidosis?
cells are starving in the midst of plenty and turn to breakdown of fats and proteins and gluconeogenesis to increase the blood glucose level; this leads to excess acetyl CoA which then lead to formation of excess ketone bodies
normal accumulation of ketone bodies in urine?
<125 mg/24 h
normal accumulation of ketone bodies in blood
<3 mg/100 mL
adipocytes prefer what energy source?
process of making glucose from non-carbohydrate intermediates, except for fatty acids (although 3-c fatty acids can be used for gluconeogenesis)
where does NADPH come from?
pentose phosphate pathway
why is NADPH important?
it is used to synthesize molecules, whereas NADH is used as a cofactor to break down molecules