CC LEC LIPIDS AND LIPOPROTEINS

Lipids

commonly referred as fats are a rich source of energy and efficient way for storage of excess calories

Steroid hormones

Lipids are also a source of what type of hormones?

Fatty acids

building blocks of lipids

Free or unesterified

Fatty acids may exist as ____________________ form in the plasma

Albumin

Where is fatty acids mostly bound to?

Saturated fatty acids

FA w/ no double bonds

Unsaturated

FA with double bonds

Triglycerides

the main storage form of lipid in the body

composed of 3 molecules of FA and a glycerol backbone

triacylglycerol

other name of triglycerides, abbreviated as TAG

Saturated triglycerides

fats coming from animal sources, solid @ room temp

Unsaturated triglycerides

oils, coming from plant sources, liquid @ room temp

Trans fats

unsaturated fat that behaves as saturated TAG

Phospholipids

composed of fatty acids and a phospholipid head group

major membrane lipid

surfactants

Surfactants

measured to know if the lungs are matured

Hydrophilic head

phosphate head

Hydrophobic tail

fatty acid tail

Cholesterol

not readily metabolized by most cells, not a source of fuel

precursor of steroid hormones, bile acid, and vitamin D

Cholesterol esters

cholesterol + fatty acid

Free cholesterol

cholesterol not attached to FA

Lipoprotein

bonding of molecules of fat and protein

Membrane

Phospholipids and cholesterol are found on the ___________ of lipoproteins

Core

Triglycerides and cholesteryl ester are found in the ___________ of lipoproteins

Apolipoproteins

"identification marker" of lipoproteins

Chylomicrons

VLDL

LDL

HDL

What are the 4 major types of lipoproteins?

Chylomicrons

What is the largest yet least dense lipoproteins?

Exogenous triglycerides

Chylomicrons transport what type of triglycerides?

Very low-density lipoproteins

Pre-B lipoprotein

Endogenous triglycerides

VLDL transports what type of triglycerides?

Liver

This organ is also capable of producing VLDL to be transported to the peripheral tissues

Low-density lipoprotein

Beta lipoprotein

Major transport protein of cholesterol and depositing them to peripheral cells

Bad cholesterol

• Atherosclerosis

• Coronary heart diseases

In LDL, plasma level is directly proportional to risk of which diseases? (2)

High-density lipoprotein

smallest yet most dense

Alpha lipoprotein

Reverse cholesterol transport

Good cholesterol

Size

Triglyceride levels correlates with the lipoprotein's:

Density

Protein levels correlates with the lipoprotein's:

Apo A-1

main distribution is in the HDL

Function: Activates LCAT with esterifies cholesterol

Apo B-100

main distribution is in the VLDL and LDL

Function: Carboxy-terminal recognition signal targets LDL to the LDL receptor

Apo B-48

main distribution is in the chylomicron

Function: not recognized by LDL receptor

Apo C-II

main distribution is in the chylomicron and VLDL

Function: Lipoprotein activator

Apo C-III

Main distribution is in VLDL and HDL

Function: Lipoprotein lipase inhibitor

Apo E-4

Main distribution CM, VLDL, IDL, Remnants, and HDL

Is associated with high LDL-C, higher risk of atherosclerosis and Alzheimer's disease

Apo E-2

Associated with type 3 hyperlipoproteinemia

Intermediate density lipoprotein

Lipoprotein A

2 minor lipoproteins

Intermediate density lipoprotein (IDL)

intermediate between VLDL and LDL

increased in patients with type 3 hyperlipoproteinemia

VLDL remnant

other name for IDL

Lipoprotein A

interferes with normal thrombosis

LDL density range

In ultracentrifugation, Lp(a) is found in the:

VLDL in electrophoresis

In electrophoresis, Lp(a) migrates with:

Sinking pre-Beta lipoprotein

Other name for Lp(a)

Lipoprotein X

Beta-VLDL

Abnormal lipoproteins (2)

Lipoprotein X

found in patients with obstructive biliary disease

abnormal lipoprotein rich in unesterified cholesterol and phospholipids

Lipoprotein X

Cathodal lipoprotein (migrates to cathode in electrophoresis)

Beta-VLDL

more cholesterol than TAG

VLDL density range

In ultracentrifugation, B-VLDL is found in what density range?

LDL in electrophoresis

B-VLDL migrates with _______ in electrophoresis

Floating Beta-lipoprotein

Other name for Beta VLDL

Lipoprotein lipase

responsible for hydrolysis of TAG in lipoproteins

ATP-binding cassette protein

responsible for efflux of cholesterol from peripheral cells into HDL

Lecithin cholesterol acyl transferase

catalyzes the esterification of cholesterol (HDL) by promoting transfer of fatty acids from lecithin to cholesterol

Cholesterol ester transport protein

transfer cholesterol ester from HDL to Apo B-100 - containing lipoproteins (VLDL and LDL) in exchange for TAG

Phospholipid transport protein

transfer of phospholipid to and from HDL, important for HDL growth and remodeling

LDL-receptor

binds ApoE and ApoB100 and mediates endocytosis of lipoproteins

Lipid absorption pathway

Exogenous pathway

Endogenous pathway

Reverse cholesterol transport pathway

4 major pathways of lipids (LEER)

Lipid absorption pathway

- Lipids from diet converted into simple forms to be absorbed

- Those lipids that are absorbed are packaged into chylomicrons

What pathway?

Exogenous pathway

Chylomicrons packaged from lipids absorbed during lipid absorption pathway, will first shrink into CM remnants first before being accepted by the liver

What pathway?

Endogenous pathway

- Lipids produced by the liver are packaged into VLDL

- VLDL will tend to go to the peripheral tissues

- On the way to the peripheral tissues, it is attacked by LPL and becomes IDL

-IDL eventually becomes LDL

-LDL will now be transported to the peripheral tissues

What pathway?

Reverse cholesterol transport pathway

- Once HDL is formed it goes back to the liver

What pathway?

Chromatographic methods

Immunochemical methods

Electrophoresis

Ultracentrifugation

4 methods of lipoprotein assay (CIEU)

Chromatographic methods

using gel chromatograph affinity

Immunochemical methods

utilize antibodies directed towards specific apoproteins

Electrophoresis

separates lipoproteins based on their electric charge followed by staining using fat stains

Ultracentrifugation

THE reference method for lipoprotein assay

separates lipoproteins based on their densities

Amido black B

fat stain

1. HDL

2. LDL

3. VLDL

4. Chylomicrons

In ultracentrifugation, order the 4 lipoproteins from densest to least dense

Chemical and enzymatic

2 methods of cholesterol determination

Extraction

Saponification

Purification

Colorimetry

4 chemical methods for cholesterol determination

Extraction

removal of cholesterol from proteins using organic solvents

Saponification

hydrolysis of cholesterol esters to FA and free cholesterol using alcohol KOH

Purification

precipitation of free cholesterol using digitonin

Colorimetry

formation of colored product

Colorimetry only. Protein, chromogen, and color differences are interferences.

1 step approach, what is done and what are its interferences?

Extraction and colorimetry. Chromogen and color differences are the only interferences.

2 step approach, what is done and what are its interferences?

Extraction, saponification, and colorimetry. Partially removed chromogen interferences.

3 step approach, what is done and what are its interferences?

Extraction, Saponification, Purification, Colorimetry done. All interferences removed.

4 step approach, what is done and what are its interferences?

Liebermann-Burchardt reaction

Salkowski reaction

2 colorimetry methods

Liebermann-Burchardt method

acetic anhydride + sulfuric acid = cholestadienyl monosulfonic acid (GREEN)

simple method of cholesterol determination

Salkowski method

Ferric iron + sulfuric acid = cholestadienyl disulfonic acid

(RED)

Green

Liebermann-Burchardt end product color

Red

Salkowski method end product color

Cholesterol esterase

Cholesterol ester + H2O = Cholesterol + fatty acid

What enzyme catalyzes this reaction?

The first enzyme of the enzymatic method of cholesterol determination

Cholesterol oxidase and Cholest-4-en-3-one

Cholesterol + O2 = Cholest-4-en-3-one + H2O2

What enzyme catalyzes this reaction and what can already be measured here?

Peroxidase and Quinoneimine dye

H2O2 + Phenol + 4-aminoantipyrine = Quinoneimine dye + H2O

What is the enzyme and what is being measured here?

500nm

Quinoneimine dye absorbance

240nm

Cholest-4-en-3-one absorbance

Polarographic method

measures amount of oxygen produced when H2O2 is reacted with peroxidase

Extraction

Saponification

Oxidation

Colorimetry

4 chemical methods for TAG determination

Extraction

removal of lipids from proteins using organic solvents

Saponification

TAG cleaved to FA and glycerol using alcoholic KOH

Oxidation

Glycerol converted to a measurable compound (formaldehyde) using sodium periodate

Formaldehyde

In colorimetry method for TAG determination, what is being measured?

Hantzch method

Acetyl acetone and ammonia (TAG determination)