Biochem Chapt 17

Front 1

Oxidation of fatty acids source of E

Back 1

1/3 of our E comes from fats (triaglycerils)

About 80% of E used for the heart and liver are from oxidation of fatty acids

Hibernating animals rely on it

Front 2

Fats provide efficient fuel

Back 2

When compared with polysaccharides:

Carry mor E per C

Carry less water (nonpolar)

Glucose and glycogen are ST w quick delivery and fats are LT w slow delivery

Front 3

Fatty acids are absorbed in the small intestines

Back 3

See pic

Front 4

Chylomicrons

Back 4

Transport lipids in blood

Front 5

Hormones trigger movement of stored triacylglycerols

Back 5

Glucagon and epinephrine attach to receptor

Adenylyl Cyclades is then g coupled to covert ATP to cAMP

cAMP activated PKA

PKA targets 2 proteins: hormone sensitive lipase and HSL

This then activates ATGL which release a triacylglycerol, HSL breaks it doesn’t to diacylgylcerol and finally MGL redcues to monoacylglycerol so we have 3 fatty acids

Fatty acids are transferred out of cell

Front 6

Lipase cleave fatty acids from glycerol

Back 6

Need a way to use both the glycerol and the fatty acids chains

Glycerol will enter glycolysis

Front 7

Glycerol from fats enters glycolysis

Back 7

Glycerol kinase activate glycerol using ATP

Cost is covered in next steps

Allows limited anaerobic catabolism of fats

Front 8

Glycerol is then oxidized

Back 8

Glycerol 3-phosphate dehydrogenase is oxidized to create dihydroxyacetone phosphate

Front 9

Transport or attachment to phospholipids conversion to fatty acyl-CoA

Back 9

1. A phosphate from ATP is attached to prime/activate fatty acid

2. Now CoA-SH is able to bond with fatty acid and rest of phosphate group leaves

Creates a fatty acyl-CoA which can be used either to build up or break down fatty acids

Front 10

Fatty acid transport into mitochondria

Back 10

Degraded in cytosol of adipose cells and then transported to other tissues for fuel

Beta-oxidation of fatty acid occurs in mitochondria

Less than 12C can diffuse across membrane but larger need transport via acyl-carnitine/ carnitine transporter (molecule in pic)

Front 11

Acyl-carnitine/carnitine transport

Back 11

Enzyme on outside switches out for carnitine

Then goes through transport molecule (cotransporter: one goes in and one goes out).

Once in mitochondria, process is reversed

Front 12

Fatty acid oxidation in mitochondria

Back 12

Stage 1: oxidative conversion of 2 C units into acetyl-CoA via beta oxidation, creating NADH and FADH2

Stage 2: oxidation of acetyl-CoA into CO2 via citric acid cycle creating NADH and FADH2

Stage 3:generates 3 ATP from NADH and FADH2 via respiratory chain

Front 13

Step 1: Beta oxidation pathway: dehydrogenation

Back 13

Remove 2 C at a time

Occurs at beta C

Remove 2 e- into repository chain resulting in trans double bond

Front 14

FAD cofactors in beta oxidation

Back 14

Allows for transfer of H and e- to for FADH2

Front 15

Step 2: hydration of alkene

Back 15

Water adds across the double bond yielding alcohol on beta C

Front 16

Step 3: dehtdrogenation of alcohol

Back 16

Use another dehydranase to remove 2 e- and 2 H

Use cofactors NAD+ (where e- and H are going)

Front 17

Contributions to respiratory chain

Back 17

2e- from FAD cofactors

2e- from NADH cofactors

Front 18

Step 4: transfer of fatty acid chain release

Back 18

Now have less stable structure

acetyl-CoA released by thiol breaking C-C bond

Front 19

For long chain fatty acids

Back 19

Use trifunctional peptide that has all of the activities together for 12 C chains or more

I’m the short chain we have separated soluble enzymes

Front 20

Oxidation of unsaturated fatty acids

Back 20

Contain cis double bonds

Need additional enzymes:

Isomerase coverts cis double bonds starting at C 3 to trans double bonds (need for monounsaturated)

Reductase reduces cis double bonds not at C3 ( need both enzymes for polyunsaturated)

The mor double bonds you introduce, the less energy you get bc step is skipped resulting in less FADH

Front 21

Odd numbered fatty acids

Back 21

Some are odd number

Propionyl-CoA (3C ) forms during final cycle of beta oxidation of odd numbered fatty acids

Bacteria also produces it in rumen

Results in methylmalonyl CoA

Needs coenzyme B12 to succinylcholine CoA (swapping H)

Contains cobalt (like heme) called corrin

Front 22

Beta oxidation in peroxisomes

Back 22

Mostly in plants

Same steps but Difference in location of e-, Preference for long chain FA, And NADH can not be reoxidized

Front 23

Pathway feedback

Back 23

See pic

Front 24

Omega oxidation

Back 24

Happens at omega C in ER of liver and kidney

Mainly on substrates of 10 and 12 C

Minor pathway but becomes important when beta oxidation cannot occur due to carnitine deficiency

Front 25

Alpha oxidation

Back 25

is used to degrade branched FA chains

Occurs in peroxisomes

Front 26

Ketone bodies

Back 26

Need oxaloacetate is needed to get ACoA into citric acid cycle

When it is depleted m, ACoA is converted into ketone bodies

3 different ketone bodies exist

Front 27

3 ketone bodies

Back 27

In liver

Acetone:

Acetoacetate

Beta hydroxybutyrate

Front 28

To make ketone bodies

Back 28

1. (Reverse of last step in beta oxidation) Take 2 molecules of ACoA to make acetoacyl CoA

A third ACoA is added. This frees up 2 CoA molecules to move to other tissues

Break down to acetoacetate and further break down to acetone

All can be used for energy purposes and if in abundance, acetone can be released

Front 29

Ketones bodies are made in kidney

Back 29

See pic