lipids Flashcards
lipid solubility
- Insoluble, must be processed to a more transportable form
- Cannot diffuse to the absorptive surface
Lipases
are water soluble
○ Only place enzyme and fat meet is oil-water interface
○ Is lipase is abundant, available surface area of lipid determines rate of hydrolysis
Triglycerides
○ Glycerol and three fatty acids
○ Fuel
○ Storage and transport form of energy
- Phospholipids
○ Glycerol, 2 fatty acids, phosphate
phospholipids are good for
○ Membranes, lipid transport, nerve
essential lipid vitamins
- Vitamins A, D, E, K
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Cholesterol precursor for
○ Bile salts
○ Steroid hormones
○ Vitamin D
cholesterol stored as
cholesterol esters (CE) (chol + fatty acids)
LCTA/ACAT catalyses
esterification
cholesterol + fatty acid = cholesterol ester
cholesterol esterases catalyse
hydrolysis
cholesterol ester to fatty acid + cholesterol
lipases catalyse
hydrolysis
triglycerides to fatty acids and glycerol
fatty acetyltransferases catalyse
esterification
fatty acids and glycerol to triglycerides
bile acids from liver/gall bladder
- Detergents
- Break up fat to make it water soluble
- Water soluble enzymes can access them
fatty acid transporter
fatty acid translocase FAT
fatty acid transport protein FATP
cholesterol transporter
Niemann- Pick disease type C1 like 1 (NPC1L1)
acyltransferases
- Triglycerides and cholesterol esters (by acyltransferases) reformed when inside the intestinal wall
§ Trapped inside the cell so they wont diffuse back out
4 stages of burning fat
- Lipolysis (TAG -> FA)
- Activation (CoA addition - requires ATP)
- Transport into mitochondrion (requires carnitine)
- B-oxidation (yields FADH, NADH, Acetyl-CoA)
3 things that happen as a response to too much cholesterol
- Inhibit synthesis
§ Inhibition of HMG-CoA reductase activity
- Block uptake
§ Reduced LDL- receptor (LDLR) expressed
- Safer storage
§ Stimulates acyl CoA: cholesterol acyl transferase (ACAT)
Plasma cholesterol
- LDL (and other remnant lipoproteins) oxidise readily
- Is then taken up by macrophages in artery walls
- Damage to endothelium and underlying smooth muscle
- Restricted blood flow, increase BP, endothelial dysfunction
