Improvement of Apolipoprotein E Phenotyping by Isoelectric Focusing/Immunofixation

Rapid apolipoprotein E phenotyping by immunofixation in agarose.

Conventional determination of apolipoprotein E isomorphs comprises ultracentrifugation of 1-5 ml serum, delipidation of very low density lipoproteins (VLDL), and isoelectric focusing (IEF) in polyacrylamide gels. In order to reduce the sample volume and to avoid nonspecific protein bands, immunoblotting was proposed. Now we describe a methodological variant that uses 25 microliters serum, repla...

Apolipoprotein E polymorphism determined by restriction enzyme analysis of DNA amplified by polymerase chain reaction: convenient alternative to phenotyping by isoelectric focusing.

Three common alleles determine six apolipoprotein E (apo E) phenotypes that are associated with variations in serum cholesterol in the population. This genetic variation results from single nucleotide alterations at two DNA loci encoding the amino acid residues 112 and 158 of apo E. We compared results of apo E phenotyping carried out by isoelectric focusing with those of apo E genotyping accom...

Improved phenotyping of apolipoprotein E: application to population frequency distribution.

A simple procedure for phenotyping apolipoprotein (apo) E directly from plasma has been developed for use in the lipid clinic laboratory. In this new method, 10 microL of serum or plasma is pretreated with neuraminidase (EC 3.2.1.18), which removes the sialic acid residues from apo E and eliminates additional bands, thereby ensuring correct phenotype assignment. After a rapid delipidation step,...

Purification of anti-apolipoprotein CIII antibodies by exploiting their affinity for apolipoprotein CIII linked to polyacrylamide gel after isoelectric focusing.

A new immunoaffinity technique for purifying anti-apolipoprotein CIII antibodies has been developed by isolating bands of apo CIII2 from isoelectric focusing (IEF) gel. Total apo C was obtained from delipidated very-low-density lipoprotein by chromatography on Sephacryl S 200. Apo CIII2 was separated from the apo CII band by IEF on polyacrylamide gel with use of pH 4-6 ampholytes. After sonicat...

Frequency of Apolipoprotein E Alleles in Iranian Populations