Picture Cards Flashcards
Recall the structure of a glycerophospholipid
Recall the structure of a sn-glycerol-3-phosphate
- 1C hydroxyl
- 2C hydroxyl
- 3C phosphate
Where is a glycerophospholipid’s headgroup located and what can this be?
- Membrane
- H (water)
- ethanolamine
- Choline
- Serine
- Signalling
- Inositol
- Glycerol
- Cardiolipin
- Phosphatidylglycerol (myocytes + prokaryotes)
What are the two strategies for generating phosphodiester linkages to activate glycerol or activate the headgroup?
- Strategy 1: diacylglycerol activated with CDP by head group
- Used more in single cells
- Activation of diacylglycerol most common in bacteria
- Strategy 2: Head group activated directly with CDP
- More abundant in mammals
In both cases, the beta phosphate in CDP is transferred to the headgroup.
Give the steps for the synthesis of phosphatidic acid (which is subsequently turned to CDP-diacylglycerol) from glycerol-3-phosphate
- Acyl chains are added in to consecutive steps as thioesters from acyl carrier protein (ACP) to generate phosphatidic acid
- sn-1 position is almost always (90%) a saturated acyl chain
- sn-2 is usually (90%) unsaturated
- Different enzymes may exist for the addition at each position
- Very costly to make membranes as you need ATP and CoA derivates at each step with different acyl transferases at each of these steps
Describe the interconversion of phospholipids
- Base exchange
- Eukaryotes can generate the necessary phospholipid species by exchanging headgroup
- Does not require energy
- Is calcium depenent
- Occurs at basic pH
- Localized to endoplasmic reticulum
Phospholipases are hydrolytic enzymes that degrate phospholipids at specific positions in order to remodel fatty acid species on the phospholipid (eg. to replace polyunsaturated fatty acids which have been damaged by oxidation). Which phospholipases snip where?
- Phospholipase A1: sn-1
- Phospholipase A2: sn-2
- Phospholipase C: Releases base and phosphate group
- Phospholipase D: Releases only the base
What are triacylglycerols?
Triglycerides. Glycerol backbone esterified to three fatty acyl chains. Dietary TAG/TG is absorbed from the intestine, transported in the plasma and stored in adipase tissue.
Recall the different representations of apolipoprotein structure
Edmunson helical wheel diagram
Draw acetyl-CoA
Recall how isoprene are assembled to make squalene
