Mid 2: Lec 9 Flashcards
3 main steps fatty acid catalysis
activation of FA
Transport of FA
Beta oxidation
FA Activation
Fatty acid to fatty acyl coa
acyl-Coa synthetase
uses 2 ATP
FA activation location
short and medium chain activated inside mit
long chain activated on cytosolic face of mit
FA transport
carnitine shuttle
allows long chain FA Coa to enter mit
- CPT1 uses carnitine and fatty acyl coa to make fatty acyl-carnitine
- fatty acyl carn passes through outer membrane through porins and through inner membrane through translocase
- CPT II converts fattyl acyl carn back to fatty acyl coa
regulation of FA catab with carnitine shuttle
CPT1 is inhibited by malonoyl coa, which is an intermediate of FA synth. catab will not occur at same time as synth.
FA beta oxidation
- dehydrogenation of acyl coa into trans delta2 enoyl coa. formation of alpha beta double bond
ACAD
Generates FADH2 which is used by ECT
- Hydration of
trans- Δ2-Enoyl-CoA to form L-3-hydroxyacyl-CoA
Catalyzed by enoyl-CoA
hydratase
- dehydrogenation
of L-3-hydroxyacyl-CoA to
form 3-ketoacyl-CoA
3-L-hydroxyacyl-
CoA dehydrogenase
generates nadh
- Thiolytic cleavage of
3-ketoacyl-CoA to form a Cn-2 acyl- CoA and acetyl-CoA
thiolase
net ATP beta oxidation include if odd num carbons
minus 2 atp for activation
-num_rounds = num_C/2 -1
1 FADH2 = 1.5 atp per round
1 NADH = 2.5 atp per round
-num ACA = num_C/2
3 NADH = 7.5 ATP per ACA
1 FADH2 = 1.5 atp per ACA
1 GTP = 1 ATP per ACA
-If odd number carbons
add 1 NADH = 2.5 atp
add 1 FADH2 = 1.5 atp
beta oxidation of polyunsaturated FA
-double bond on odd number carbon:
enoyl coa isomerase changes 3-4 double bond to alpha beta double bond
minus 1 fadh2 = 1.5 atp
-double bond on even number carbon
dienoyl-coa reductase and enoyl coa isomerase
minus one nadph = 2.5 atp
ketogenesis overview and where
takes place in liver when levels of glucose in the blood are low and other carbohydrate stores are exhausted
gluconeogenesis leads to decreased oxaloacetate levels
decreased oxa levels decreases TCA efficiency
this combined with FA beta oxidation leads to buildup of ACA
ACA is converted to ketone bodies which can be converted to energy
Ketogenesis steps
- thiolase turns two ACA to one acetoacetyl coa
- HMG coa synthase adds another ACA to result in HMG coa
- HMG coa lyase converts hmg coa to acetoacetate
4a. Reduction of acetoacetate to form β-hydroxybutyrate by D- β-hydroxybutyrate
dehydrogenase
4b. Step4b: Spontaneous decarboxylation of acetoacetate
to acetone (or by the action of acetoacetate
decarboxylate)
role of ketone bodies during starvation and fasting (inc 2 types)
liver produces acetoacetate and beta hydroxybutyrate
these are utilized as an alternative fuel by peripheral tissues
