Lab 9 - Lipids Flashcards
Solubility of lipids
Insoluble in water, soluble in fat solvents
How does the lipids differ from each other, and what kind of groups of lipids do we have?
In chem. structure.
- Simple: esters of FA with glycerol. Gen. found in organisms as triacylglycerols. Saturated or unsaturated. Function: E storage.
- Derivated lipids - lipoids: Cholesterol is important. Phosphatides also.
How can simple esters be transferred in the organism?
By the blood circ. to the fat tissue to be stored as dipot fat, or transported from the dipot to the user organs in form of free FA.
Common unsaturated FA
Oleic acids. In plants high proportion of more unsaturated FA is common (linoleic, linolenic acids)
Where is cholesterol synthesized?
Liver
Function of cholesterol as lipid
- Precursor of steroid hormones and bile acids.
- Constituent of bio. membranes.
Function and example of phosphatides as lipids
- Membrane constituents
- E.g. Lecithin
How is long chain FA transported?
From fat depot to the user organs (muscle, liver) by the blood. Bound to albumin with sec.bonds.
How can a long chain FA be detached?
By Cu(II)sulphate/CuSO4 or Cu(II)nitrate/Cu(NO3)2 from the albumin. The produced copper salt can be dissolved in chloroform.
How does quantitative estimation of FFA work?
After detaching FA from albumin with Cu(II)-reagent:
The nr. of Cu2+ in the chloroform is the same nr. as FA, and can be measured by diethyldithiocarbamate by photometry.
Copper II reagent
Triethanol amine, acetic acid and copper sulphate solution
Materials in “quantitative estimation of FFA”
- Copper(II) reagent
- Na-diethyldithiocarbamate
- Chloroform
How is cholesterol transported in the organism?
Fro the site of synthesis (liver, intestinal wall, gonades) to user tissue while bound to albumin. Can be transported either in free or esterified form (by FA).
What is the principle method for measuring the totalt cholesterol conc. of the blood plasma?
- In presence of glacial acetic acid and sulphuric acid, FeCl3 will oxidize cholesterol and form new unsaturated double bonds.
- Two of these oxidized cholesterol molecules are able to bind to each other and prod. conjugated double bonds –> purple color.
- The intensity of the color can be measured with spectophotometry.
Materials in “measuring the cholesterol conc. of the blood”?
- Blood plasma
- FeCl3 solution: FeCl3 dissolved in glacial acetic acid
- Colour reagent: FeCl3 with conc. sulphuric acid
- Glacial acetic acid
Which diseases can be diagnosised with help from measuring cholesterol level?
- Hyperlipidaemia
- Some hepatic diseases (hepatopathies)
- Hyperadrenocorticism
- Hypothyreosis
Normal amount of total cholesterol in:
- dogs
- cats
- herbiivores
- dogs: 2,5-8 mmol/l
- cats: 2-6.5 mmol/l
- herbivores: 1,5-5 mmol/l
How are triglycerides transported?
In chylomicrons and diff. types of lipoproteins (VLDL, LDL, IDL, HDL) in the blood plasma.
Which enzymatic reactions is used to measure triglycerides conc. in blood plasma?
- Triglycerides transported in lioproteins are hydrolysed to glycerol and FA by lipoprotein lipase.
- Glycerol kinase enzyme converts glycerol to glycerol-3-P by using one ATP molecule.
- Glycerol-3-phosphate oxidase (GPO) oxidizes glycerol-3-P to dihydroxyacetonephosphate. At the same time H2O2 is released, by using O2 from air.
- The prod. H2O2 is converted to water by peroxidase enzyme (POD), while a red quinone derivate is prod.
Function of glycerol-3-phosphate oxidase (GPO)
Group of aerobe dehydrogenases. The prod. FADH2 passed the hydrogens directly to oxygen of the air, and H2O2 is released.
How can we measure the triglycerides conc. after the enzymatic reactions?
The red quinone derivate can be measured by spectrophotometry.
Materials in “measuring triglycerides conc. in blood”
- Blood plasma
- Colour reagent: enzymes and colour forming substrates (4-aminoantipyrine and phenol) dissolved in phosphate buffer.
- Standard triglyceride sol.
How is prim. bilde acids prod.?
During degradation of cholesterol in the liver.
Primary bile acids?
Cholic acid and chenodeoxycholic acid
How is bile acids excreted?
Their salts with taurine and glycine are excreted in the bile, and get into the small intestine.
Role of bile acids?
Have detergent effects; play role in digestion and absorption of lipids.
Principle method for determination of cholic acid from bile?
- Taurocholic acid and glycocholic acid will be determined.
- Sucrose is turned into hydroxymethyl furfural by conc. sulphuric acid.
- Oxymethyl furfural prod. a coloured complex with cholic acid.
Materials in “determination of cholic acid from bile”?
- Bile
- Sucrose sol.
- Conc.sulphuric acid
How is the E gain in lactation in dairy cows covered by?
-Lipid mobilization from the fat depots; lipolysis is incr. in the adipose tissue, where FFA are released into the blood and taken up by the liver. In the liver they enter beta-oxidation.
What happens at the same time as lipid mobilization?
- GNG in hepatocytes prod. a huge amount of glucose for lactose synthesis, so OAC also enters GNG.
- The high amount of Ac-CoA prod. in beta-ox. can´t enter citrate cycle because of lack of OAC, so they enter ketogenesis.
- Therefore hepatocytes prod. high amount of KB.
Example of ketone bodies
Acetone, acetoacetate, beta-hydroxybutirate
Where are ketone bodies released and how are they used?
Released in blood stream and utilized by extrahepatic tissues in ketolysis.
What happens in dairy cows in beginning and peak of lactation?
Ketogenesis is so intensive that the whole amount of the prod. KB can´t be broken down in ketolysis, therefor KB accumulate in blood and will be excreted by urine and milk –> ketosis disease develops
- Hyperketonaemia
- Keonuria
- Ketolactia
- KB in blood
- KB in urine
- KB in milk
Proportion of ketone body conc. in diff. bio. fluids?
Milk : blood : urine = 1 : 5 : 10
Principle method in detection of ketone bodies from urine and milk
Sodium nitroprusside forms a purple coloured complex with acetoacetate and acetone in the presence of ammonia.
