Fatty Acid Oxidation and Ketogenesis Biochem

Fatty acid oxidation (Beta Oxidation) aerobic or anaerobic

aerobic

identify and calculate the energy generated from beta oxidation of one molecule of 16:0 (Palmitic Acid)

8 acetyl CoAs

80 ATPs from CAC and Respiratory chain

7 FA oxidation cycles occur forming 7 NADH and 7 FADH2= 28 ATPs from Respiratory chain

2 ATPs used to form acyl CoA initially for transport into mitochondria

TOTAL NET 106 ATPs from C 16 SFA

332 ATP from 1 triacylglycerol vs ATP from 1 glucose aerobically

identify the structure of ketone bodies, their utilization and excretion in the body

Ketogenesis occurs in the mitochondria of liver cells. Used as energy source by brain and skeletal muscle.

identify the biosynthesis and regulation of ketogenesis

Occurs after FA is oxidized to acetyl CoAs

1. 3 acetyl CoA +H2O → HMG CoA +2 CoA via HMG CoA synthase

2. HMG CoA→ acetoacetate +acetyl CoA via HMG CoA lyase

3. A) acetoacetate→ acetone(secreted unto blood and is excreted in breath,urine,sweat

4. B) acetoacetate + NADH+ H+ ← → 3-hydroxybutyrate + NAD+ via 3-hydroxybutyrate dehydrogenase

what is Ketogenesis

metabolic pathway that produces ketone bodies, which provide an alternative form of energy in the body

Increased FA oxidation occurs during glucose deficiency and leads to

ketogenesis in the liver

FA can be oxidized and synthesized from

acetyl CoA

Steps of Lipolysis.

1. Triacylglycerol —> glycerol + 3 free FA via hormone sensitive lipase

2. in blood, FFA bind to albumin while glycerol circulates freely

3. FFA removed from blood by active muscles/liver while glycerol removed only by the liver

Glycerol Metabolism steps:

occurs in cytosol of liver

1. glycerol +ATP ——> glycerol 3-phosphate+ADP via glycerol kinase

   1. glycerol 3-phosphate + NAD+ ←→ DHAP +NADH + H+ via glycerol dehydrogenase

2 glycerol molecules produce what products in glycerol metabolism

2 DHAPs which enter gluconeogenesis to produce 1 glucose

Fatty acid oxidation (Beta Oxidation) occurs with what type of fatty acid

saturated fatty acid

Fatty acid requires a special mechanism to transport the FFA through mitochondrial membranes. List the steps of this process.

1. FFA + CoA + ATP → Acyl CoA +AMP + PPi via Acyl CoA synthetase.

2. Acyl CoA passes thru outer membrane into intermembrane space. Acyl CoA + carnitine → acylcarnitine + CoA via carnitine palmitoyl transferase I

3. Acylcarnitine transported into matrix via carnitine acylcarnitine translocase

4. in matrix acylcarnitine + CoA→ acyl CoA + carnitine via carnitine palmitoyl transferase II

5. Acyl CoA→ Oxidation

Saturated Fatty Acid Oxidation Cycle Steps

1. sat acyl CoA + FAD→ un sat acyl CoA + FADH2 (FADH2 produces 1.5 ATPs by the respiratory chain.)

2. unsat acyl CoA + H2O → hydroxy acyl CoA

3. hydroxy acyl CoA + NAD+ → ketoacyl CoA + NADH (NADH produces 2.5 ATP’s by the respiratory chain)

4. ketoacyl CoA + CoA → Acetyl CoA+ sat acyl CoA. (this sat acyl group is 2 carbons shorter than in step 1)

5. acetyl CoA goes into the CAC producing 10atps

6. new satacyl CoA goes back to step 1 and repeats the cycle

   Process continues until FA is completely oxidized into indiviual acetyl CoAs

the major ketone bodies in the body 3

1. acetoacetate

2. 3- hydroxybutyrate

3. acetone

Ketone Body Catabolism

Once acetoacetate and 3-hydroxybutyrate are secreted into the blood and removed by brain and skeletal muscle for energy

1. 3-hydroxybutyrate + NAD+ ←→ Acetoacetate+ NADH + H+

2. acetoacetate + succinyl CoA→ succinate + acetoacetyl CoA

3. acetoacetyl +CoA + CoA ←→ 2 acetyl CoAs

Enter CAC