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CHEMICAL AND PHYSICAL PROPERTIES OF APOLIPQPROTEIN OF VERY LOW DENSITY LIPOPROTEIN FROM EGG YOLF GRANULES
Author(s) -
KOCAL J. T.,
NAKAI S.,
POWRIE W. D.
Publication year - 1980
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1980.tb07605.x
Subject(s) - chemistry , chromatography , electrophoresis , molecular mass , gel electrophoresis , urea , polyacrylamide gel electrophoresis , tetramethylurea , elution , agarose , molecular weight size marker , biochemistry , gel electrophoresis of proteins , enzyme , solvent
Tetramethylurea (TMU) was used to delipidate very low density lipoprotein from egg yolk granules [VLDL(MF)] and dissociate the apoproteins into subunits prior to gel electrophoresis. Electrophoretic analysis indicated the presence of three apoproteins, one of which was a complex of the other two. SDS disc gel electrophoresis of the proteins extracted from the TMU gels demonstrated that each band was heterogeneous, containing many polypeptide bands. SDS polyacrylamide gel electrophoresis dissociated apoVLDL(MF) into 22 polypeptides (molecular weights ranging from 9,600‐136,000) in the presence of urea, dodecyl sulphate and 2‐mercaptoethanol. Fourteen of these bands were glycoproteins reacting positively with the Schiff reagent. This heterogeneity of polypeptides is due in part to slight differences in the carbohydrate bound to the apoprotein. Electrophoresis devoid of 2‐mercaptoethanol resulted in resolution into only 18 bands, most of which contained higher molecular weight aggregates not present in the reduced samples. The apo‐VLDL(MF) was fractionated on 6% agarose columns containing 8M urea or 2 mM dodecyl sulphate. TWO apoprotein fractions were eluted from the SDS column, and three from the urea column. The protein eluted at the void volume of the urea column was a complex aggregate of the other two proteins; urea was not as good a dissociating agent as dodecyl sulphate. A similarity was found between the fractions eluted from the SDS column and the proteins extracted from the TMU gels; the polypeptides identified by SDS gel electrophoresis had identical electrophoretic patterns. The molecular weights of the two apoproteins from the SDS column were analyzed by sedimentation equilibrium techniques. The molecular weight range for the high molecular weight component was 33,300‐165,800 and 5,800‐28,100 for the low molecular weight component. It appears that the apoprotein isolated from egg yolk granules has similar protein moiety to that from egg yolk plasma and hen's plasma.