Seperation of serum lipoproteins of various domestic animal species by numerous precipitation methods

128 7. SUMMARY Lipoproteins are water-soluble complexes through wich fats and lipids are transported between the various tissues for storage and utilization. Association of lipoproteins with risk of coronary heart disease and various types of dyslipoproteinemias necessitates the quantification of the individual lipoprotein classes. One of the most commonly used techniques for the separation of P and pre-P lipoproteins is the precipitation tecnique. However, none of the lipoprotein separation techniques used in laboratories has been developed for use in animal lipoproteins. It was suggested that lipoprotein separation preosedures might require modification before they are applied to the plasma of a given animal species. Therefore, the present study was undertaken to compare the concentrations of precipitation reagents ( heparin/MnCİ2, dextran sulfate/MnCk, sodyum fosfotungstat/ MgCk, polyethylene glycol) necessary in order to precipitate p + pre-P lipoproteins in human and various animal sera. To this end, firstly human serum lipoproteins and later the serum lipoproteins (P + pre-P) of the various animal species were precipitated using various precipitation methods. The lipoproteins precipitated were separated by agarose gel electrophoresis. In accordance with the original heparin/MnCİ2 precipitation method being commonly used for human serum, 200 IU heparin / 46umol MnCl2 yielded complete precipitation of p + pre-P lipoproteins in sera from all the animal species investigated. Wheras bovin serum required approx. 2 times more heparin/MnCİ2 for the precipitation of same lipoportein classes than did human serum whereas chicken serum required half of the reagent concentration. Addition of dextran sulfate/MnCİ2 at the concentration used for human serum resulted in complete precipitation of P + pre-P lipoprotein of sera from all animal species. In sodyum fosfotungstat/MgCl2 precipitation method, p + pre-p lipoproteins of goat and sheep were precipitated by two times more sodyum fosfotungstat/MgCİ2 than that required for human serum p + pre-p lipoproteins. In other animal species P + pre-P lipoproteins were precipitated by the same sodyum fosfotungstat/MgCl2 concentration as human lipoproteins. As with the human serum, employment of 13% polyethylene glycol resulted in full precipitation of p + pre-p lipoproteins of all the animal species except chicken. With the chicken serum half the concentration of polyethylene glycol was used as compared to human serum.129 The serum p + pre-P and a lipoproteins precipitated by sodyum fosfotungstat/MgCfe and dextran sulfate/MnCfe methods were completely dissociated and consequently separated by agarose gel electrophoresis. However, with the heparin/MnCİ2 method complete dissociation and electrophoretical separation of the lipoproteins precipitated was not achieved. Apolipoprotein compositions of the lipoproteins ( p + pre- p ) fully precipitated were analyzed by SDS-PAGE. It was concluded that the concentrations of polyanion/divalent cation and neutral polymers used for the precipitations of serum p + pre-P lipoproteins differ between human and several animal species. The existing differences might be attributed to the variations in charge densities of lipoproteins' surface as well as to dissimilarities in lipid compositions of the lipoproteins between species.