Chapter 27 - Lipid Oxidation Flashcards
4 classes of lipid
- fatty acids
- triacylglycerols (triglycerides)
- phospholipids
- cholesterol
Fatty acid carbon atoms are usually numbered beginning with…
the carboxyl terminal carbon atom
Carbom atoms 2 and 3 are referred to as..
alpha and beta
Fatty acids can also be numbered from the methyl carbon atom, which is called….
omega carbon
fatty acids, a major source of energy, are stored as….. in adipose tissue
triacylglycerols in lipid droplets
adipose tissue depots
- pulmonary
- periadventitial
- perirenal
- bone marrow
- epicardial
- subcutaneous
- visceral
triacylglycerols
the most concentrated form of stored energy available to animals; 37kJ/g
-highly reduced
Carbohydrates energy content
16 kJ/g
protein energy content
17 kJ/g
triacylglycerols are stored in what form?
anhydrous
Which get depleted quicker… triacyglycerols or glycogen?
glycogen; only lasts hours
Excessive triacylglycerol storage in adipose tissue can lead to..
obesity
High levels of triacylglycerol in blood can lead to…
heart attack/stroke
Since triacylglycerol is too hydrophobic to cross biological membranes, how is it transported/digested (in the small intestine)??
it is degraded in the small intestine and resynthesized in intestinal mucosal cells
lipases
break down lipids
chylomicron
a lipoprotein synthesized only in intestine that allow for transport of insoluble lipids in the blood stream to tissues
chylomicron composition
phospholipid and cholesterol on the surface, triacylglycerol in the core
lipoprotein lipase
bound to cell surface and releases all 3 fatty acids from each TG
lipid droplets
- have a phospholipid monolayer instead of bilayer
- core is hydrophobic where TG is stored
perilipin
- protein on surface of lipid droplet
- barrier to lipases
- prevents unwanted TG breakdown
lipolysis
TG broken down to glycerol and 3 FA
- phosphorylation of perils-in allows lipase access to TG in lipid droplet
- activates adipose tissue TG lipase
phosphorylation of hormone sensitive lipase
activates hormone sensitive lipase
Fate of fatty acid and glycerol
glycerol goes to liver, FA to muscle
FA oxidation occurs in..
the mitochondria
To be oxidized, FA needs to be:
- activated (bound to CoA)
- transported (carnitine shuttle)
fatty acyl CoA
a generic term describing any fatty acid bound to CoA
Activation of fatty acid to fatty acid CoA (reversible)
- fatty acid reacts w/ ATP to form an acyl adenylate and other two phosphorylation groups of ATP substrate are released as pyrophosphate
- the sulfhydryl group of CoA attacks acyl adenylate to form acyl CoA and AMP
Activation of acid to fatty acid CoA driven by?
hydrolysis of pyrophosphate by pyrophosphates to 2 organic phosphates
transportation of fatty acid CoA
The acyl group is transferred from the sulfur atom of CoA to the hydroxyl group of carnitine to form acyl carnitine.
transportation of fatty acid CoA catalyzed by:
carnitine acyltransferase I, which is bound to the outer mitochondrial membrane:
rate-limiting step of fatty acid oxidation
fatty acid transport into the mitochondria
carnitine shuttle while fasting
highly active
carnitine shuttle while fed
low activity
4 basic steps of B-oxidation of saturated fatty acids (degradation of fatty acids)
- oxidation
- hydration
- oxidation
- cleavage
Overall equation for the oxidation of palmitate
Palmitoyl CoA + 7CoA +7FAD + 7NAD+ + 7H2O –> 8Acetyl CoA + 7FADH2 + 7NADH + 7H+
Net ATP production of oxidation of palmitate?
106 ATP
Enoyl CoA isomerase
- moves double bond from C3-4 to C2-3
- changes double bond from cis to trans
ketone bodies
- alternative to glucose as a fuel or energy source
- formed by ketogenesis in liver
- produced at low rate
- utilized by extra hepatic tissues when glucose is low(starvation)
- used after several days of fasting (prevents use of protein and tissue breakdown)
condensation of 3 acetyl CoA forms?
acetoacetate
acetoacetate is converted to what
3-hydrocybutyrate and acetone
Metabolism of Ketone Bodies in extrahepatic tissues (brain) occurs in?
the mitochondria
excess production of ketone bodies can lead to ..
acidosis
