Lyposlysis, Fatty Acid Oxidation, and Metabolism

Question 1

Triglyceride Lipases

Answer 1

Break triglycerides into fatty acids and glycerol via lypolysis
Both products of this reaction are released into plasma
FA circulate bound to albumin and are called free fatty acids

Question 2

Enzymes for lypolysis

Answer 2

ATGL (adipose triglyceride lipase) major one

HSL (hormone sensitive lipase) mainly for diglycerides

MGL (monoglyceride lipase) for monoglycerides

Question 3

Lipoprotein lipase

Answer 3

Acts with circulating TG rich molecules (VLDL, chylomicrons) to facilitate uptake of FA into adipocyte.
This enzyme is made and secreted by adipocytes and gets lodged in EC capillary endothelium.

Question 4

NEFA (non-esterified fatty acids)

Answer 4

Free fatty acids

Question 5

Fate of triglycerides

Answer 5

Fatty acids become as oxidative fuel or ketone bodies in liver.
Glycerol becomes available for gluconeogenisis in liver and kidney.

Question 6

Location of fatty acid metabolism

Answer 6

In mitochondria. Leads to preferred source of oxidative metabolism in muscle.

Question 7

CD36

Answer 7

protein involved in taking FA into cells. Process not known.

Question 8

Fatty-Acyl CoA

Answer 8

What fatty acids taken into the cell are turned into by Fatty-Acyl CoA Synthases.

Question 9

Carnitine

Answer 9

Zwitterion attached to fatty acid instead to Acyl-CoA by Carnitine-Acyl transferases I (CAT1) to allow fatty acid to go into mitochondrion.
CAT2 is on the outer side of the inner mitochondrial membrane.

Question 10

Malonyl-CoA

Answer 10

Allosterically inhibits CAT1.
Establishes inverse relationship between FA synthesis and FA oxidation in liver
Presence of Malonyl-CoA governs the switch from using glucose of FA for energy

Question 11

ACC-B (Acetyl-CoA Carboxylase-B)

Answer 11

Makes Malonyl-CoA in the process of FA synthesis

This happens most when glucose is readily available

Question 12

Carnitine-Acyl transferase 2

Answer 12

Enzyme on the matrix side of mitochondria, reforms fatty acyl-CoA

Question 13

Beta-oxidation pathway

Answer 13

Once inside mitochondrial membrane, the 16-Carbon Palmitoyl-CoA undergoes 7 oxidation cycles to yield 8 Acyl CoAs, each with 2 Cs.
-Each oxidation cycle produces 1 FADH2 in first step and 1 NADH in 2nd step, to be used in ETC.
-8 Acyl-CoAs are available for combustion in Krebs cycle
if oxaloacetate is present (means some glucose is still needed)

Question 14

Ketone bodies

Answer 14

• Acetoacetate and B-hydroxybutyrate made in liver via ketogenesis (organic acids)
• can be made available to brain
• adaptation to starvation

-when glucose and therefore oxaloacetate is low, acetyl-CoA can’t be used in the citrate cycle, the latter is taken through ketogenesis.

Question 15

Monocarboxylase transporter (MCT1)

Answer 15

Takes ketone bodies into cells.

Ketones are oxidized mainly in muscle and brain