Triglycerides and Fatty Acid Metabolism Overview

Triglycerides (TGs)

Three fatty acids ester-linked to a glycerol backbone.

Storage of triglycerides

In adipose tissue.

Efficiency of fatty acids as energy store

They store energy without water and yield more energy per gram.

Energy provided by glucose

17 kJ/g

Energy provided by palmitic acid

38 kJ/g

Process breaking down triglycerides

Lipolysis.

Proteins transporting free fatty acids (FFA) in blood

Human Serum Albumin (HSA).

First intracellular step of fatty acid metabolism

Activation to Acyl-CoA by Acyl-CoA synthetase.

ATP equivalents used in fatty acid activation

2 ATP equivalents.

Molecule transporting fatty acids into mitochondrial matrix

Carnitine.

Enzyme swapping CoA for carnitine

Carnitine Acyltransferase I.

Enzyme reattaching CoA inside mitochondrial matrix

Carnitine Acyltransferase II.

Main process breaking fatty acids into 2C units

β-oxidation.

Products of one β-oxidation cycle

1 Acetyl-CoA, 1 NADH, 1 FADH₂.

Cycles palmitic acid (C16) goes through

7 cycles.

Total ATP generated from one palmitic acid molecule

131 ATP total, 129 ATP net.

Products from final cycle of odd-chain fatty acid oxidation

Acetyl-CoA (2C) and Propionyl-CoA (3C).

Trigger for ketone body formation

Excess Acetyl-CoA in the liver during prolonged starvation.

Three ketone bodies

Acetoacetate, β-hydroxybutyrate, Acetone.

Ketone body exhaled or lost from body

Acetone.

Conversion of ketone bodies in destination tissues

Acetyl-CoA.