Biochem Fa Oxidation

Front 1

how are dietary fats utilized?

Back 1

absorbed in small intestine, converted to TAGs and packaged into chylomicrons, enter lymphatics and drain into left subclavian vein, and in circulation lipoprotein lipase on endothelial cell surfaces cleaves fatty acids

Front 2

how are store fats utilized?

Back 2

hormonal signals trigger release of fatty acids from store TAGs in adipose tissue, and they circulate bound to albumin

Front 3

when stored fatty acids are released, what are they bound to?

Back 3

albumin
(most abundant protein in blood)

Front 4

what activates hormone sensitive lipase?
when is hormone sensitive lipase activated?

Back 4

phosphorylation by PKA
when epinephrine or glucagon GPCR activates adenylate cyclase

Front 5

what does hormone sensitive lipase do?

Back 5

cleave an acyl group (fatty acid) from diacylglycerols

Front 6

what enzyme cleaves a fatty acid from triacylglycerols?

Back 6

desnutrin
(aka adipose triglyceride lyase)

Front 7

when are fatty acids cleaved from TAGs?

Back 7

constitutively
(TAGs are in equilibrium with DAGs since the regulated enzyme, hormone-sensitive lipase, does not work on TAGs)

Front 8

what enzyme cleaves a fatty acid from monoacylglycerols (to make glycerol molecules)?

Back 8

MAG lipase

Front 9

where does fatty acid oxidation take place? why?

Back 9

mitochondrial matrix
to avoid breaking down newly synthesized fatty acids (which are in cytosol)

Front 10

what enzyme converts FFAs into acyl-CoA molecules so that they can move into the intermitochondrial space?

Back 10

acyl-CoA synthase

Front 11

what enzyme adds a carnitine to acyl-CoA molecules?

Back 11

carnitine palmitoyl-transferase 1
aka CPT1
aka CA1
(located on outer mitochondrial membrane)

Front 12

which enzyme transports acylcarnitine molecules across inner mitochondrial membrane?

Back 12

carnitine acylcarnitine translocase
(located on inner mitochondrial membrane)
(connects pumping of acylcarnitine into matrix and carnitine out)

Front 13

which enzyme transports carnitine molecules across inner mitochondrial membrane?

Back 13

carnitine acylcarnitine translocase
(located on inner mitochondrial membrane)
(connects pumping of acylcarnitine into matrix and carnitine out)

Front 14

what enzyme cleaves carnitine from acylcarnitine molecules, producing acyl-CoA molecules?

Back 14

carnitine palmitoyl-transferase 2
aka CPT2
aka CA2
(located on inner mitochondrial membrane)

Front 15

where are all enzymes of FA oxidation located?

Back 15

inside mitochondria

Front 16

what are the steps in fatty acid oxidation?

Back 16

oxidize, hydrate, oxidize, split

Front 17

what molecule are converted to ketone bodies by liver cells?

Back 17

acetyl-CoA

Front 18

what is the drawback of beta-oxidation?

Back 18

can't get ATP without oxygen like you can with anaerobic glycolysis

Front 19

what is the last molecule remaining in fatty acid oxidation of fats with odd-numbered carbons?

Back 19

propionyl-CoA, which is converted to succinyl-CoA

Front 20

how many additional enzymes does oxidation of unsaturated fatty acids require?

Back 20

two

Front 21

what is the disease caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH)?

Back 21

Refsum Disease

Front 22

what methylated fatty acid cannot be broken down in Refsum Disease?
where is this FA found?

Back 22

phytanic acid
found in ruminant tissues and dairy products

Front 23

what are the important clinical features of Refsum disease?

Back 23

retinitis pigmentosa
chronic polyneuropathy
cerebellar ataxia
elevated CSF protein
severe motor weakness
muscle wasting in lower extremities

Front 24

what drug therapy can present symptoms like those of Refsum disease? why?

Back 24

FK506 drug therapy
PHYH binds to FK506

Front 25

what effect does insulin have on the amount of lipoprotein lipase?

Back 25

increases levels in adipose tissue

Front 26

what effect does starvation have on lipoprotein lipase levels?

Back 26

decrease in adipocytes
increase in cardiac tissue (also increases amount oxidative enzymes and decreases fat synthesis enzymes)

Front 27

what hormones increase activation of hormone sensitive lipase? how?

Back 27

glucagon and epinephrine
increase PKA mediated phosphorylation

Front 28

what effect does AMPK have on hormone sensitive lipase? how?

Back 28

inhibits
phosphorylation

Front 29

what effect does insulin have on hormone sensitive lipase? how?

Back 29

activates
removes cAMP from blood, rendering PKA inactive, so that it cannot phosphorylate hormone sensitive lipase

Front 30

what molecule inhibits carnitine acyltransferase I?

Back 30

malonyl-CoA

Front 31

what type of patients can display carnitine deficiencies?

Back 31

preterm newborns
patients on hemodialysis

Front 32

what will be the end result of systemic carnitine deficiency?
what would be the end result if the deficiency was limited to muscle?

Back 32

sytemic - death
muscular - cramping to severe weakness

Front 33

what effect does CA-1 deficiency have on the liver?

Back 33

reduced FA oxidation
reduced ketogenesis

Front 34

what is the difference between primary deficiencies and secondary deficiencies?

Back 34

primary are caused by lack of synthesis, whereas secondary is caused by whatever is deficient being trapped somewhere

Front 35

what effect does CA2 deficiency have?

Back 35

pain and fatigue in skeletal muscle
myoglobinuria following exercise

Front 36

what are the symptoms of an acyl-CoA dehydrogenase deficiency?
what can alleviate/prevent these symptoms?

Back 36

vomiting
lethargy
coma

frequent feedings

Front 37

what is the primary ketone body in the blood?

Back 37

beta-hydroxybutyrate

Front 38

what conditions must be met in the liver for it to initiate ketogenesis?

Back 38

excess acetyl-CoA
not enough carbon source for glucose

(response to starvation or fasting)

Front 39

what intermediate is common between cholesterol metabolism and ketogenesis?

Back 39

HMG-CoA

Front 40

what enzyme is the same in the brain as in the liver, but due to NADH/NAD ratio acts in reverse?

Back 40

beta-hydroxybutyrate dehydrogenase

Front 41

where is HMG-CoA lyase found? why?

Back 41

only in mitochondria
because in cytosol, would inhibit cholesterol synthesis in well-fed conditions

Front 42

what enzyme is not present in liver, inhibiting it from utilizing ketone bodies?

Back 42

beta-ketoacyl-CoA transferase
(aka succinyl-CoA transferase)
adds CoA from succinyl-CoA to acetoacetate

Front 43

what is the primary regulator of ketogenesis?

Back 43

substrate availability

Front 44

what are the two possible fates for fatty acids in the liver?

Back 44

ketone bodies
TAG synthesis

Front 45

when will acetyl-CoA be utilized in the TCA cycle? what happens to ketogenesis in this state?

Back 45

when ATP demand is high
ketogenesis does not occur

Front 46

what enzyme, dependent on hormonal regulation, helps to regulate ketogenesis?

Back 46

ACC